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- Front Matter: Volume 8421
- Fiber Optic Gyro I: 35 Anniversary Workshop
- Fiber Optic Gyro II: 35 Anniversary Workshop
- Fiber Optic Gyro III: 35 Anniversary Workshop
- Fiber Optic Gyro IV: 35 Anniversary Workshop
- Special Workshop on Industrial Progress, Commercial Systems, and Field Tests I
- Special Workshop on Industrial Progress, Commercial Systems, and Field Tests II
- Special Workshop on Industrial Progress, Commercial Systems, and Field Tests III
- Special Workshop on Industrial Progress, Commercial Systems, and Field Tests IV
- Plenary Session
- Physical and Mechanical Sensors I
- Micro- and Nano-structured Fiber Sensors I
- Distributed Sensing I
- Physical and Mechanical Sensors II
- Micro- and Nano-structured Fiber Sensors II
- Slow and Fast Light, and Other Emerging Technologies
- Smart Structures and Sensor Multiplexing
- Biomedical and Chemical Sensors I
- Biomedical and Chemical Sensors II
- Fiber Grating Sensors
- Distributed Sensing II
- Sensor Application and Field Tests
- Poster Session 1: Physical, Mechanical, Electromagnetic, and Fiber Grating
- Poster Session 2: Biomedical and Chemical Sensor, Micro-structured Fiber Sensors, Sensor Multiplexing
- Poster Session 3: Fiber Optic Gyroscopes, New Fibers and Coating Materials, Distributed Sensing, Sensor cont.
- Post-Deadline Manuscripts
Front Matter: Volume 8421
Fiber Optic Gyro I: 35 Anniversary Workshop
Fiber optic gyros past, present, and future
Show abstract
This paper will review the technical developments that brought the fiber optic gyro from the laboratory to production.
Selected Northrop Grumman fiber optic gyro based products will be then reviewed at a high level. Finally, potential
future developments in fiber optic gyros that are being examined by researchers around the world will be reviewed.
The fiber-optic gyroscope: actually better than the ring-laser gyroscope?
Hervé C. Lefevre
Show abstract
The fiber-optic gyroscope started to be investigated 35 years ago, opening the way for a fully solid-state rotation sensor.
It was firstly seen as limited to medium-grade applications, but today, it reaches ultimate theoretical performance and
surpasses its well-established competitor, the ring laser gyroscope, in terms of bias noise and long-term stability.
Fiber optic gyro R&D at Beihang University
Chunxi Zhang,
Ningfang Song,
Lijing Li,
et al.
Show abstract
Beihang University has been carrying out systematic research from basic theory to industrialization of fiber optic
gyroscope (FOG). Through the study on basic theory and establishment of physical and mathematical model, simulation
platform is formed for the analysis of FOG system.. Production lines are established for integration, test and
manufacture of components and FOG products. The test results of our typical products indicate that high performance
FOG has a bias stability of 0.0008°h in laboratory, and three-axis FOG has a bias stability of better than 0.01°/h.
Fiber Optic Gyro II: 35 Anniversary Workshop
Fiber optic gyros in a high-performance, high-reliability inertial reference unit for commercial satellites
S. Sanders,
A. Taranta,
S. Mosor,
et al.
Show abstract
Honeywell Space Systems Division has successfully completed development of the Interferometric Fiber Optic
Gyroscopes (IFOG) for a next-generation Inertial Reference Unit (IRU) to point commercial satellites. The design,
build, and test phase of an engineering-model of this IRU, nicknamed Spirit, completed in 2011. The Spirit IRU
complements the existing portfolio of Honeywell navigation products, such as the Miniature Inertial Measurement
Unit (MIMU), by leveraging the long life and excellent performance inherent in FOG technology. This paper
provides an overview of the Spirit system along with initial results from gyro performance and life testing.
Interferometric closed loop fiber optical gyroscopes for commercial and space applications
Show abstract
The design and industrial production of closed loop fiber optical gyroscopes with linear digital output for commercial,
military and space applications is considered. These gyros characterized by high accuracy can be applied in high-grade
(space, aviation, marine, land) inertial navigation systems.
Fiber Optic Gyro III: 35 Anniversary Workshop
Resonator fiber optic gyro progress including observation of navigation grade angle random walk
Show abstract
A benchtop experimental resonator fiber optic gyro (RFOG) was assembled and tested. The gyro employed a fiber length of
19 meters of polarizing fiber for the sensing coil which was wound on a 4.5 inch diameter piezoelectric cylinder. Angle
random walk (ARW) values in the range of 0.0075 to 0.0085 deg/rt-hr were observed against a calculated shot noise limit
of 0.0053 deg/rt.-hr for this experimental arrangement. To our knowledge, this is the first ARW result reported for an
RFOG that is consistent with commercial navigation-grade performance.
Resonator fiber optic gyro with bipolar digital Serrodyne Modulation Scheme
Show abstract
We have proposed and studied a resonator fiber optic gyro (R-FOG) with bipolar digital serrodyne phase modulation scheme. The serrodyne modulation serves multiple functions from reducing noises caused by fiber characteristics, such as backscattering and optical Kerr effect, to achieving gyro signal processing including closed-loop operation. Because the sensing fiber length in R-FOG is much shorter than that in interferometer FOG (I-FOG), the Shupe effect, which is caused by temporally variant temperature distribution along the fiber, can effectively be reduced in R-FOG. In this paper, a resonator made of a polarization-maintaining optical fiber (PMF) with twin 90o polarization-axis rotated splices has been proposed to suppress the polarization-fluctuation induced drift. An automated control to optimize the suppression has been proposed and demonstrated in experiments. To suppress the backscattering induced noise effectively, a precise adjustment of amplitude of the bipolar digital serrodyne waveform has also been introduced. Additionally, a closed-loop operation has been demonstrated by locking both the frequencies of clockwise (CW) and counter clockwise (CCW) travelling lightwaves to the resonator's resonant frequencies with manipulating the serrodyne waveform.
Fiber Optic Gyro IV: 35 Anniversary Workshop
Improving fiber optic gyroscope performance
using a laser and photonic-bandgap fiber
Show abstract
Based on insights from a new model of scattering in FOGs for high-coherence sources, we demonstrate experimentally
that a fiber optic gyroscope (FOG) can be driven with a laser of suitable linewidth and exhibit short and long-term
performance matching that of a FOG driven by a broadband source. This innovation can be combined with the use of
hollow-core fiber in the sensor coil to produce new FOGs exceeding current standards.
Truly single-mode polarization maintaining hollow core PCF
Show abstract
Fabrication of a truly single mode, low loss and polarization maintaining HC-PCF is reported. This fiber has a 50 nm
wide strictly single mode region with good polarization holding (h-parameter below 10-4 m-1) and low loss (<20 dB/km).
Polarization maintaining photonic crystal fiber IFOG
Show abstract
Polarization maintaining (PM) photonic crystal fiber (PCF) and Er-doped PCF technologies are investigated for
interferometer fiber optic gyroscope (IFOG) applications. A PM-PCF optimized to achieve low-loss and high
polarization extinction splice-joints with conventional PM fiber pigtails of a multifunction integrated optical circuit
(MIOC) was drawn and tested under different temperature conditions. The loss and polarization crosstalk
properties of a fiber coil made from the PM PCF were measured and compared with conventional PM fiber. An
erbium-doped PCF was designed and fabricated, with which a superfluorescent fiber source (SFS) was made and tested.
The results show that an IFOG with the PM-PCF coil and the Er-doped PCF source could achieve better temperature
performance. An experimental PCF-based prototype IFOG was built and tested , and preliminary results was obtained.
Special Workshop on Industrial Progress, Commercial Systems, and Field Tests I
Optical coherence tomography and optical smart sensing
Show abstract
Optical coherence tomography (OCT) has been developed particularly for biomedical and industrial fields owing to the
advantage of in vivo real time optical imaging with a micro-scale high resolution. Depending on specific imaging
purposes, various dedicated OCT systems have been proposed and implemented. We present the recent achievements of OCT systems and their applications such as monitoring of cross-sectional biological specimen, discrimination of living human breast cancer cells, and characterization of wet pad surface in chemical mechanical polishing (CMP) process.
Fiber optic sensors shine bright: industrial applications where FOS bring differentiated performance/value
Show abstract
Fiber Optic Sensors have been the topic of numerous conferences over the past 30 years,
including the 22 International OFS meetings. These events, driven predominately by academic and
research institutions, have helped develop the science of fiber optic sensing, and served an important role
in growing the knowledge base in this field. The applications of fiber sensors has always been an
important topic for discussion but, apart from a few notable exceptions, it has been a slow progression
from lab-bench to realizing true differentiated, value-added, commercial applications for fiber sensors.
The past decade has, however, been a tipping point for the commercial success of fiber optic sensors,
particularly in industrial applications. This paper will review some of these advances and highlight areas
where fiber optic sensors bring true commercial benefits in industrial settings.
Special Workshop on Industrial Progress, Commercial Systems, and Field Tests II
Fiber-optic strain sensors are making the leap from lab to industrial use: reliability and validation as precondition for standards
Show abstract
Fiber-optic sensors are increasingly used if special requirements avoid the application of electrical sensors, or economic
benefit is promised. The scientific background is well developed; however, there are some restrictions with respect to
long-term reliable use. For a widespread practical use, sensor products must be manufactured, characterized and
validated according to standards. Guidelines on how to apply sensors and evaluate their operation on-site including
special facilities to evaluate applied sensors are needed. The paper will present validation methods to evaluate the quality
of sensor systems function. It will also indicate lacks of knowledge and methods to be filled to promote the use of FOS.
Fiber optic sensors and their applications on structural health monitoring in South Korea
Show abstract
Fiber optic sensors can be used to measure some physical quantities through long optical fibers applied on structures.
Three types of fiber optic sensors, fiber Bragg grating sensor, Brillouin OTDR(optical time domain reflectometry) and
Raman OTDR(optical time domain reflectometry), are mostly useful to sense structural health status. In my works,
multiplexing of FBG sensors, Raman OTDR and fiber optic BOTDA(Brillouin Optical Time Domain Analysis) sensor
will be introduced in this presentation. Novel auto correction Raman OTDR can only sense temperature without any
influence, such as bending losses. Double pulse technique is introduced to enhance spatial resolution of BOTDA. An
error compensation of distributed strain measurement is also developed to get precise strain measurement using the
BOTDA sensor. Finally, the applications of fiber optic sensors are shown in several fields including aerospace, civil
structures and wind turbine blades in South Korea.
Research on optic fiber sensing engineering technology
Show abstract
The research on engineering experiment is a key step in translating technical development to industrial application.
According to our practical experience for more than 30 years and some applications of the fire alarm system, bridge, coal
and power safety ensuring system, this paper reviews on engineering technique problems in the application of fiber optic
sensor and their solutions, which may provide some references for wider industrial applications.
Special Workshop on Industrial Progress, Commercial Systems, and Field Tests III
Raman sensors and their applications
Arthur H. Hartog
Show abstract
Distributed temperature sensors (DTS) based on Raman optical time-domain reflectometry (OTDR) are now
commonly used in a wide range of industries. This paper summarises the state-of-the-art DTS systems, including
recent developments, and describes some important applications.
Recent progress in distributed optical fiber raman sensors
Show abstract
A brief review of recent progress in researches, productions and applications of distributed fiber Raman sensors at China
Jiliang University (CJLU) is presented. In order to improve the measurement distance, the accuracy, the space resolution,
the ability of multi-parameter measurements, and the intelligence of distributed fiber sensor systems, a new generation
fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new
generation distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distributed
fiber Raman and Rayleigh scattering sensors integrated with a fiber Raman amplifier (FRA), auto-correction full
distributed fiber Raman temperature sensors based on Raman correlation dual sources, distributed fiber Raman
temperature sensors based on a pulse coding source, distributed fiber Raman temperature sensors using a fiber Raman
wavelength shifter, a new type of Brillouin optical time domain analyzers (BOTDA) integrated with a fiber Raman
amplifier, distributed fiber Raman and Brillouin sensors integrated with a fiber Raman amplifier, and distributed fiber
Brillouin sensors integrated with a fiber Brillouin frequency shifter. Sensor networks are important components of the
internet of things. The distributed optical fiber sensor network (Rayleigh, Raman, and Brillouin scattering) is a 3S (smart
materials, smart structure, and smart skill) system, which is easy to construct smart fiber sensor networks. The
distributed optical fiber sensor has been applied to the power grids, railways, bridges, tunnels, roads, constructions, water
supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.
Fiber optic asset integrity monitoring using Brillouin-based distributed sensing for the oil and
gas and energy industries: challenges and achievements
Show abstract
Asset integrity monitoring based on distributed fiber optic monitoring using BOTDA is playing an increasingly
important role in today’s oil and gas and energy industries. Existing applications, part of operator’s asset integrity
management plans are as diverse as fatigue monitoring of subsea umbilicals, thermal optimization of direct electrical
heated subsea flowlines, pipeline leak and ground movement detection and 3D pipeline deformation monitoring or
thermal management of offshore wind farm electrical export cable. The monitoring solutions developed and qualified by OMNISENS over the last decade are now installed world wild, providing 24/7 event detection and localization for its
valuable customers.
Special Workshop on Industrial Progress, Commercial Systems, and Field Tests IV
Development of fiber-optic current sensing technology for electric power systems
Kiyoshi Kurosawa
Show abstract
This paper describes development and applications of a fiber-optic electric current sensor with stable properties and
compact, simple, and flexible structure. The special characteristics of the sensor were achieved with use of special low
birefringent fiber as the Faraday-effect sensing element, and were also achieved with creation of a sensing scheme which
matches with the properties of the fiber. Making use of the excellent features of the sensing technology, various current
monitoring devices and systems were developed and applied practically for control and maintenance in electric power
facility. In this paper, examples of field tests and practical applications of such systems are introduced, including fault
section/point location systems for power transmission cable lines.
Fiber optic acoustic sensing
Clay Kirkendall
Show abstract
A review of fiber optic acoustic sensors for naval applications is presented. Limitations of fiber interferometric sensors
are described and novel acoustic sensor transducers enabled through fiber laser sensor technology are presented.
Recent progress toward fiber optic hydrophone research, application and commercialization in China
Show abstract
The fiber optic hydrophone research in China has a history of over 20 years. This talk will summarize some remarkable
millstones in this history. Recent progress toward the fiber optic hydrophone research and application will be discussed.
Some commercialization explorations will also be introduced.
Fiber optical sensor trends in the energy field
Show abstract
The raising demand for increase of efficiency and reduction of costs in power generation causes a mind change and
promotes the commercial use of fiber optical sensors for health monitoring and control purposes.
Plenary Session
Optical nanosensors and nanoprobes: from single-cell exploration to medical diagnostics
Show abstract
This lecture presents an overview of recent advances in the development of optical nanobiosensor and nanoprobe technology at the nexus of engineering, biology, medicine and nanotechnology. The presentation describes two areas of research related to the development of nanoprobes and nanosensors for biomolecule detection and single-cell analysis : (1) plasmonics nanoprobes using surface-enhanced Raman scattering (SERS) detection; and (2) nanobiosensors for in vivo analysis of a single cell for molecular diagnostics and imaging, and ultra-high throughput screening. Novel nanobiosensors and nanoprobes combining bio-recognition and nanotechnology have been developed for in-vitro molecular diagnostics and in-vivo monitoring of biological targets and biochemical processes in a single living cell. These studies demonstrate applications of plasmonics “molecular sentinel” nanoprobes for diagnostics of diseases such as cancer and the use of nano-biosensors for measurements of molecular signaling pathways inside a single cell. Fiberoptics-based nanobiosensors are used to detect apoptotic processes in single cells following photodynamic cancer treatment or to monitor pH in cancer cells. These nanodevices open new possibilities to a wide range of applications in medical diagnostics at the point of care, global health, molecular imaging, biology research, ultra-high throughput screening, and investigations of the therapeutic action of pharmaceutical agents.
Physical and Mechanical Sensors I
Development of nano-strain-resolution fiber optic quasi-static strain sensors for geophysical applications
Show abstract
We report a series of nano-strain resolution fiber-optic static-strain sensors by use of fiber Bragg gratings and fiber
Fabry-Perot interferometers, for the monitoring the crustal deformation in geophysics research field. These sensors have
identical references for static strain measurement, and the resolution and dynamic range are guaranteed by the
interrogation methods. With the fiber Bragg grating sensor, field demonstrations on the monitoring of crustal
deformation induced by oceanic tide have been carried out with nano-strain resolution. Development of high
performance fiber Fabry-Perot interferometer sensor is also introduced.
Compact flexural disc accelerometers based on optical microfiber
Show abstract
The minimum bend radius of optical microfiber allows very compact flexural disc accelerometers to be manufactured
without significant degradation of the optical signal in terms of attenuation and depolarization. Such compact sensors
have potentially very high responsivity in small packages. We demonstrate a responsivity of 4 rad/g between 100-1000
Hz for a disc wound with microfiber of 60-millimeter length and 10-micron diameter microfiber. We report the
successful fabrication of a 0.4-meter length and 10-micron diameter microfiber using a new tapering setup and an
automated technique is proposed for efficiently winding long lengths of microfiber onto the flexural disc.
A passive frequency noise insensitive fiber strain sensor using post processing
Show abstract
Laser frequency fluctuations limit the ultimate resolution in interferometric fiber sensors. In this work, we demonstrate
an interferometric sensor insensitive to the effects of frequency change in an interrogating laser. A system is
characterized showing a minimum of 4.5 orders of magnitude frequency change reduction, and a demonstrated
broadband improvement of up to 1.5 orders of magnitude for signals between 100 mHz and 1 Hz. Using this technique a
resolution of less than a nanostrain/rtHz was achieved for a broad range of frequencies.
Rocking filter in microstructured fiber for high resolution hydrostatic pressure measurements
Show abstract
We report on sensing characteristics of the rocking filter fabricated in specially designed microstructured fiber with
enhanced sensitivity to hydrostatic pressure. The filter shows a very high sensitivity to pressure ranging from 16.2 to
32.2 nm/MPa, depending on the resonance order. Extremely low cross-sensitivity between pressure and temperature
27÷66×103 K/MPa has also been recorded and therefore the rocking filter can be used for pressure measurements with
mbar resolution with no need for temperature compensation.
All-fiber acceleration sensor with temperature self-compensation
Show abstract
An all-fiber accelerometer with temperature self-compensation based on Fabry-Pérot interferometer (FPI) and
simple-supported beam is proposed, where the two reflectors are the joint face between single mode fiber (SMF) and
hollow core fiber and the end face of the micro fiber used as vibration beam, respectively. The temperature effect could
be compensated by choosing proper material for the beam because it is movable in the FPI cavity. When the beam length
composed of SMF is 6 cm and the mass block is ~1.3218×10-7 Kg, the acceleration sensitivity is ~0.35 V/g and the
temperature sensitivity is less than 1pm/°C;.
Micro- and Nano-structured Fiber Sensors I
Temperature compensated, humidity insensitive, high-Tg TOPAS FBGs for accelerometers and microphones
Show abstract
In this paper we present our latest work on Fiber Bragg Gratings (FBGs) in microstructured polymer optical fibers
(mPOFs) and their application as strain sensing transducers in devices, such as accelerometers and microphones. We
demonstrate how the cross-sensitivity of the FBG to temperature is eliminated by using dual-FBG technology and how
mPOFs fabricated from different grades of TOPAS with glass transition temperatures around 135°C potentially allow
high-temperature humidity insensitive operation. The results bring the mPOF FBG closer to being a viable technology
for commercial applications requiring high sensitivity due to the low Young's Modulus of polymer.
Temperature-independent pressure sensor using triangular-shape of suspended-core fiber
Show abstract
In this work, fiber in-line Mach-Zehnder Interferometer (MZI) based on triangular-shape suspended core fibers (SCFs) is
investigated. The sensitivity of the sensing head was determined for pressure and temperature, respectively. The sensitivities
are 0.4 pm/psi and 13 pm/psi for longitudinal and radial pressure, respectively. The sensing head was also subjected to
temperature and presented very low sensitivity.
Discrimination of chemical vapor and temperature effects by using a polarization-maintaining photonic crystal fiber interferometer
Show abstract
A reflection-type interferometer based on a polarization-maintaining photonic crystal fiber (PM-PCF) is investigated
for simultaneous measurement of chemical vapor and temperature. The PM-PCF with a length of 2.6 cm is
fusion-spliced to standard single-mode fiber and airholes of the PM-PCF are fully collapsed allowing the excitation
of different core and cladding modes in the PM-PCF corresponding to two orthogonal polarization modes. Since
airholes at the end of the PM-PCF interferometer are left open, a chemical vapor can be infiltrated into the voids.
Different sensitivities corresponding to input polarization states are utilized for discrimination between chemical
vapor and temperature effects.
Femtosecond laser microstructuring through optical fibre end faces: inscription of surface gratings and sub-surface splitters
Show abstract
We present the results of femtosecond laser microstructuring of optical fibres by direct access of the fibre end face, both
at the surface and several hundred microns into the fibre, to realise one- and two-dimensional grating structures and
optical fibre splitters, respectively. We show the versatility of this simple but effective inscription method, where we
demonstrate classic multiple slit diffraction patterns and show the potential for coarse wavelength division multiplexing
for sensor signals. A key advantage for the fibre splitter is that the inscription method avoids the use of oil immersion
that compensate for the fibre curvature in the standard side writing method.
Compact optical microfiber components based on small size piezoelectric ceramic transducer
Show abstract
Optical microfibers have attracted much attention in recent years due to its physical flexibility and low bending loss,
which enables the possibility to make compact active optical components when combined with small-size piezoelectric
ceramic transducers. Here, we present the demonstration of OM embedded in low refractive index polymer wound
around a piezoceramic rod of 1 mm diameter and 6 mm length as a compact optical phase modulator, which showed a
frequency response up to 1 MHz. We also report the fabrication of a compact tunable optical resonator from a 3 mm
diameter, 1 mm thick piezoceramic disc with a 50 pm shift when 600 V is applied across its electrodes.
Distributed Sensing I
Fast and distributed Brillouin time domain analysis of optical fibers
Show abstract
We present two recently developed new methods for fast and distributed strain/temperature sensing in optical fibers,
based on Brillouin optical time domain analysis (BOTDA). Both methods make use of very fast (<1ns) and controlled
tuning of the optical frequency of a light wave. In the Fast BOTDA (F-BOTDA) method the complete Brillouin gain
spectrum is scanned, while in the Slope-Assisted technique (SA-BOTDA) only a single frequency point on the slope of
the Brillouin gain spectrum is probed. A sensing speed of a few hundred Hz is experimentally demonstrated, limited only
by the fiber length and the need for averaging.
Signal-to-noise ratio improvement in Brillouin optical correlation domain analysis combining Brillouin gain and loss effects
Show abstract
A novel scheme is proposed to measure Brillouin gain spectrum in an optical fiber combining Brillouin gain and loss
effects. A dual-parallel Mach-Zehnder modulator is used to generate upshifted afterward downshifted single sideband
with suppressed carrier by periodically chopping the dc bias. The two successive single sidebands serve as Brillouin
pump and probe waves to amplify and absorb the carrier wave for lock-in detecting of the net Brillouin gain between
Brillouin gain and loss effects. The signal-to-noise ratio of the cost-effective measurement system with fewer optical
devices is twofold enhanced. Distributed strain sensing ability with a nominal spatial resolution of 1.6 cm is
experimentally demonstrated by utilization of this scheme into a Brillouin optical correlation domain analysis system.
High-spatial-resolution distributed vibration measurement using time-resolved optical frequency-domain reflectometry
Show abstract
A high-spatial-resolution distributed optical fiber vibration sensor is demonstrated. The distributed dynamic strain or
vibration information can be obtained using time-resolved optical frequency-domain reflectometry (OFDR). Time-domain
information is resolved by measuring Rayleigh backscatter spectrum in different wavelength ranges which fall in
successive time sequence due to the linear wavelength sweep of the tunable laser source with a constant sweeping rate.
This time-resolved local Rayleigh backscatter spectrum shift of the vibrated state with respect to that of the non-vibrated
state along the fiber length provides dynamic strain information in a distributed manner. The measurable frequency range
of 0-32 Hz with the spatial resolution of 10 cm can be achieved
High-resolution Brillouin fiber sensing using random phase coding of the pump and probe waves
Show abstract
Distributed temperature measurements with 1.2 cm resolution based on stimulated Brillouin scattering (SBS) in standard
fibers are reported. High resolution is achieved by phase-coding both pump and probe waves with a high-rate, pseudo-random
binary phase code. The SBS interaction is effectively confined to narrow correlation peaks. The separation
between adjacent peaks, signifying the unambiguous measurement range, scales with the length of the modulation code
and can therefore be made arbitrarily long. Measurements were performed over 40 meters of fiber, or 3300 resolution
points. The technique is applicable to distributed measurements of birefringence and Brillouin frequency shift over
polarization maintaining fibers.
100km BOTDA temperature sensor with sub-meter resolution
Show abstract
Temperature or strain sensing in long-range (> 70 km) Brillouin Optical Time Domain Analysis (BOTDA) below 2
meter resolution cannot be trivially achieved due to numerous matters such as fiber attenuation, self-phase modulation,
depletion, resolution-uncertainty trade-offs, etc. In this paper we show that combining Raman assistance and the
Differential Pulse-width Pair (DPP) technique sub-metrical resolution is achievable in a BOTDA over 100 km sensing
range. We successfully demonstrate the detection of a 0.5 meter hot-spot in the position of worst contrast along the fiber.
Physical and Mechanical Sensors II
Multiphase flow characterization using optical fiber Bragg gratings
Show abstract
Optical fiber Bragg grating strain sensors are used to characterize the multiphase flow of water and air in a laboratory
test bed. The load applied by the fluid flow on the fiber gratings is the underlying mechanism of the sensor and different
flow conditions with distinct void fractions and flow rates were investigated. The optical fiber sensors performance was
compared against that of a wire-mesh system which is conventionally used as a reference high performance measurement
tool for multiphase flow. Results are in good agreement showing the potential of the technique.
Remote laser-driven solar cell power sources for sensors and devices via kilometer-long optical fibres
Show abstract
The use of solar cells to drive sensors with optical pumping using readily available laser sources over kilometer lengths
is proposed. A simple evaluation finds near IR transmission around 1000-1070 nm is optimal. As proof of principle, we
demonstrate a simple humidity sensor powered by solar cell through a 2 km optical fibre link using the 1057 nm output
of a Nd:YLF solid state laser.
Distributed birefringence measurement of a polarization maintaining fiber with a 20cm resolution over a 500m range based on Brillouin dynamic grating
Show abstract
We demonstrate a distributed birefringence measurement of a polarization-maintaining fiber with a 20 cm resolution
over a 500 m fiber based on Brillouin dynamic grating with the scheme including a CW pump1, a 20 ns square pump2
pulse, and a 2 ns square probe pulse. The measurement results show ~ 3% fluctuation of the birefringence over the entire
500 m fiber. We also observed the birefringence change caused by the uneven stress as winding the fiber around a spool
with a spatial period of 49 cm and the residual stress during the fiber drawing and coating processes.
A fiber-tip Fabry-Perot pressure sensor with graphene diaphragm
Show abstract
A miniature fiber-tip pressure sensor was built by using an extremely thin graphene film as the diaphragm. The
graphene also acts as a light reflector which, in conjunction with reflection at the fiber end/air interface, forms a low
fineness Fabry-Perot cavity. The graphene-based micro-cavity sensor demonstrated a pressure sensitivity of ~34.8
nm/kPa with a diaphragm diameter of ~ 25 μm, nearly two orders of magnitude higher than previously reported sensors
with similar diaphragm diameters.
Micro- and Nano-structured Fiber Sensors II
In-fiber integrated optic devices for sensing applications
Show abstract
A brief introduction is given to the state-of-the-art of in-fiber integrated optics which includes in-fiber multi-waveguideds
integration, in-fiber functional elements fabrication and in-fiber interferometers developments. The
characteristics of in-fiber integrated devices are summarized and methods for their fabrication are also described.
Examples of sensing are shown that it have the potential to be exploited in a variety of wide applications.
Suspended core optical fibers for biological applications using UV wavelengths
Show abstract
We have demonstrated the use of suspended core optical fibers as dip sensors for biological applications based on
fluorophores operating at UV wavelengths for the first time. In this paper, we have demonstrated the use of suspended-core
fibers to measure the fluorescence of 7-Amino-4-methylcoumarin (AMC), which is used as the transduction for the
standard enzyme activity assay of PC6, a biomarker of women's uterine fertility. Concentrations down to 500 nM have
been measured using a 2.1 μm core diameter fiber.
High-sensitivity force measurement using optical tapered fiber with optical frequency-domain reflectometry
Show abstract
Optical fiber taper is proposed to be a high-sensitivity force sensor by using high-resolution, high-sensitivity optical
frequency-domain reflectometry technique. The cross-correlation wavelength shift in the uniform region of taper is
related to the refractive index change of the fundamental mode. The wavelength-force sensitivity of a fiber taper is
dramatically improved due to its reduced waist diameter. It was demonstrated that that a taper with a waist diameter of
~6μm has a force resolution of 6.35μN and a force sensitivity of 620.83nm/N, which is about 500 times higher than that
of SMF, over its uniform taper range with a spatial resolution of 3.85mm.
Fabrication of a micro-cantilever sensor on a single mode fibre by picoseconds laser
Show abstract
Micro-cantilevers are one of the most popular Micro-Electronics-Mechanical-Sensor (MEMS).They've demonstrated in
a number of application areas such as chemical and bio-sensing. However, these devices usually need the alignment of
the cantilever with the read-out system, which can be challenging. Furthermore, it involves a bulky free-space optical
detection system. In this paper, we propose techniques to design and fabricate micro-cantilevers onto the end of standard single mode fibres using a picoseconds (ps) laser machining technique. In this way the cantilever can be aligned with the core of the fibre therefore offering stable and accurate means of optically addressing the cantilever. Low-cost optical sources and fibre coupled spectrometers are employed to interrogate the final cavity with a resolution around 15nm. Experiment show this optical fibre cantilever can be used as a displacement sensor with a dynamic range up to 7μm. Proof-of-concept experiments demonstrate that the cantilever could also be used as a temperature sensor in the range of 24-320°C with a temperature sensitivity of 0.5°C.
Lab on fiber technology: towards multifunctional optical nanosensors
Show abstract
We introduce a reliable fabrication process enabling the integration of dielectric and metallic nanostructures on the tip of
optical fibers. It involves conventional deposition and nanopatterning techniques typically used for planar devices, but
here adapted to directly operate on optical fiber tip. Following this approach, we demonstrate a first technological
platform based on the integration, onto the optical fiber tip, of two-dimensional (2D) hybrid metallo-dielectric
nanostructures supporting localized surface plasmon resonances (LSPR), that can be efficiently used for label free
chemical and biological sensing and as a microphone for acoustic wave detection.
Slow and Fast Light, and Other Emerging Technologies
A brillouin fast light fiber laser sensor
Show abstract
We present and theoretically study a superluminal fiber laser based super-sensor utilizing Brillouin
gain. The white light cavity condition is attained by introducing a phase shift component
comprising an additional cavity into the main cavity. By properly controlling the parameters of the
laser cavity and those of the phase component it is possible to attain sensitivity enhancement of
many orders of magnitude compared to that of conventional laser sensors. The tradeoffs between
the attainable sensitivity enhancement, the cavity dimensions and cavity roundtrip loss are studied
in details, providing a set of design rules for the optimization of the super-sensor.
Time/frequency coding for Brillouin distributed sensors
Show abstract
In this paper, we propose a novel coding for long range Brillouin Optical Time Analysis (BOTDA) distributed sensors
based on a combination of time and frequency pulses, resulting in an additional coding gain of √2 with respect to
traditional intensity-modulated codes. The generation of frequency-chirped pseudo-arbitrary pulses in return-to-zero
(RZ) format with a Direct-Digital Synthesizer (DDS) is presented and the coding gain is experimentally verified,
perfectly matching its theoretical value.
Probing molecular absorption under slow light propagation using a photonic crystal waveguide
Show abstract
High-resolution infrared absorption spectroscopy of acetylene gas is demonstrated in dispersion-engineered photonic
crystal waveguides under slow light propagation. Individual absorption profiles are obtained for both TE and TM
polarizations for group indices ranging from 1.5 to 6.7. Experimental enhancement factors of 0.31 and 1.00 are obtained
for TE and TM polarization, respectively, and are confirmed by time-domain simulations. We experimentally
demonstrate that molecular absorption is a function of the electric field distribution outside the photonic crystal slab and
the group index under structural slow-light illumination.
Spontaneous backscattering in Brillouin dynamic gratings
Show abstract
The performance of systems employing Brillouin Dynamic Gratings may suffer from noise generated by the spontaneous
Brillouin processes. It is experimentally demonstrated that spontaneous emissions, accompanying the signal of interest,
contain not only the probe spontaneous Brillouin backscattering but also a significant contribution from the co-propagating
writing pump. For a strong enough writing pump and even moderate probe power levels, the observed noise
is dominated by the pump, exhibiting an average backscattered power more than 30 dB stronger than that of the probe
alone.
Smart Structures and Sensor Multiplexing
A fiber sensor network using fiber optic power supply
Show abstract
A wide-area sensor network based on fiber optic power supply is reviewed. This sensor network is composed of
hundreds of sensor nodes driven by the laser power. Each sensor node produces optical signals by modulating a part of
the supplied laser light and sends these signals to a monitoring station. The optical power required for driving one sensor
node is less than 2 mW. Because each sensor node can control two or three sensors, a single laser diode with 1 W is
sufficient for driving 1,000 sensors. The proposed sensor network can also be integrated with wireless sensors, which
enables ubiquitous sensing.
Wavelength/frequency-division multiplexing of heterodyning fiber grating laser sensors with the assistance of CO2-laser treatment
Show abstract
In this paper, we demonstrate the implementation of a 1×10 array of heterodyning fiber grating laser sensors, pumped by
a single 980 nm laser diode. The sensors are wavelength-multiplexed by inscribing fiber gratings with different periods
and frequency-multiplexed in the RF domain with the assistance of CO2-laser treatment. Through the side irradiation
from the CO2 laser, the intra-cavity birefringence can be significantly changed and the output frequency of the individual
lasers can be continuously adjusted. The frequency range that can be achieved is as much as 1.5 GHz. As a result, the
multiplexing capability of this kind of sensor is greatly improved.
Multichannel fiber optic heterodyne interferometer for the acoustic detection of partial discharges
Show abstract
A multichannel interferometric system is proposed for the ultrasonic detection of partial discharges using intrinsic fiber
optic sensors that may be immersed in oil. It is based on a heterodyne scheme which drives at least four sensor heads in
order to localize the source of the acoustic emissions. The optoelectronic implementation and the experimental tests are
presented to optimize the resolution (4 channels - 4 mrad). In addition, the results of ultrasound measurements at 150-
kHz with an optical fiber sensor immersed in water in an acoustic test bench are shown, in which a resolution better than
10 Pa was obtained.
Biomedical and Chemical Sensors I
GRIN microendoscopes for high resolution in-vivo fluorescence imaging in small animals
Show abstract
Intravital imaging of small animal models is a powerful technique in basic and preclinical studies. Due to the physical
size of conventional microscope optics, there is a need to carry out extensive surgery procedures so as to expose tissues
of an organ during each imaging session. This limits the length of time and periodicity of each imaging session for the
same animal, thus results in low experimental throughput. Advancements in micro-optics and fiber optics technology
have paved way in removing such physical constraints. In this study, we fabricate high quality micro-endoscope based
on graded-index lenses for carrying out minimally invasive imaging procedures in live animals.
Demonstration of a flexible, highly sensitive catheter for high resolution manometry based on in-fibre Bragg gratings
C. Bueley,
P. Wild
Show abstract
This work presents a fibre optic-based flexible catheter for high resolution manometry, with sensing pods located at a
pitch of 10 mm and an overall diameter of 2.8 mm. In-fiber Bragg gratings act as the sensing elements within these
sensing pods. Absent in each sensing pod are rigid anchor points representing a novel departure from comparable designs
and resulting in increased sensitivity and decoupling from axial loading. A pressure sensitivity of 1.8 pm/mmHg and
axial sensitivity of 11 mmHg/N of applied load is demonstrated. Crosstalk between individual sensors is characterized
and a compensation scheme is developed and validated.
A refractive index sensor based on near-surface-core fiber
Show abstract
A Michelson interferometer based on near-surface-core fibers (NSCF) was demonstrated and applied to measure the
refractive index (RI) of NaCl solution. The reference arm and the sensing arm of the interferometer are constituted by a
single mode fiber and a chemical-etching near-surface-core fiber, respectively. Two different samples were tested. The
wavelength shift of the interference spectrum with the variation of the environmental refractive index was investigated.
The results show that the proposed sensor has a measurement resolution up to 120nm/RIU in the range of 1.333-1.3684.
Furthermore, the resolution can be increased by adjusting the parameters of the NSCF reasonably.
Refractive index sensing measurement based on periodically tapered small core singlemode fibre
Show abstract
An all-fibre refractive index sensor with a simple periodical tapers configuration is proposed and investigated
experimentally. The proposed fibre refractive index sensor consists of a small core singlemode fibre with tapers
periodically fabricated along the fibre using a focused CO2 laser beam, and sandwiched between two standard
singlemode fibres. Such a structure can be used for sensing of refractive index by measuring the dip wavelength shift of
the multimode interference within the small core fibre cladding. A minimum sensitivity of 125 nm/RIU is measured for a
refractive index of 1.33 and a maximum sensitivity of 383 nm/RIU for a refractive index of 1.38. The proposed
refractive index sensor benefits from simplicity and low-cost and achieves a competitive sensitivity compared with other
fibre-optic sensors.
Detection of molecular oxygen by magnetic field interaction with guided light within an optical fiber
Show abstract
We report a novel fiber-optic sensing architecture for the detection of paramagnetic gases that exploits the interaction of
a magnetic field with guided light to detect an active gaseous medium within a hollow-core photonic bandgap fiber. This
first demonstration of a fiber-based Faraday Rotation Spectroscopy (FRS) sensor operates at 762.309 nm for the
detection of molecular oxygen. The optical fiber sensor has a 14.8 cm long sensing region and 4.2 nL detection volume.
A measured FRS spectrum with a signal-to-noise ratio of 9.5 proves the principle of this new gas sensor architecture.
Biomedical and Chemical Sensors II
Optical coherence elastography: Strain imaging in tissue using optical coherence tomography
Show abstract
Optical coherence elastography (OCE) is a strain imaging technique that characterizes the elastic properties of tissues
with microscopic resolution in three dimensions. In OCE, the displacement introduced to tissue by mechanical excitation
is measured using optical coherence tomography. The local strain is calculated from the spatial derivative of
displacement to generate strain images, known as elastograms. To validate elastograms, we compare them to a finite
element analysis model of sample deformation. We also present preliminary OCE measurements performed on excised
human breast tissue, and demonstrate discrimination of tissue types based on their elastic properties.
High-speed measurement of refractive index using dielectric multilayer films deposited on optical fiber end
Show abstract
We have recently developed a refractive index (RI) sensor using a band-pass filter (BPF) composed of dielectric
multilayer films deposited on an optical fiber end. An optical spectrum analyzer was, however, conventionally employed
in this sensor to obtain the reflection wavelength, which limited the total measurement speed due to its second-order
sweep time. In this study, we enhance its measurement speed by use of a high-speed demodulator where the optical
wavelength information is converted into electrical voltage using the linear slopes of the reflection spectra. The response
time of the sensor, which is influenced by the dynamic behavior of the sample liquid, is found to be as short as several
tens of micro-seconds. We also compare its RI sensitivity with that of a simple Fresnel-based RI sensor.
Analysis of fiber-optic probes using graded-index fiber microlenses with non-ideal refractive index profiles
Show abstract
Fiber-optic probes for sensing and imaging applications often employ sections of graded-index (GRIN) fiber to re-focus
the diverging light from the delivery fiber. Such GRIN fiber microlenses possess aberrations which can cause
significant distortions of the focused output beam. Using a numerical beam propagation method, we analyze the
output beams resulting from index profiles that exhibit a central dip or a deviation from the ideal parabolic shape.
Our method is in good agreement with experimental data and it enables the accurate simulation of fiber probes for
biomedical applications using non-ideal or custom-engineered GRIN fibers with arbitrary refractive index profiles.
Development of gold nanorod-based localized surface plasmon resonance optical fiber biosensor
Show abstract
A localized surface plasmon resonance (LSPR) based optical fiber biosensor using gold nanorods has been developed.
The LSPR optical fiber sensor was fabricated by immobilizing gold nanorods at the distal end of a multimode fiber. The
surface of gold nanorods was further functionalized with human IgG to create a biosensor to detect anti-human IgG. The
peak shift of the longitudinal plasmon wavelength of gold nanorod was monitored as a function of the refractive index
change. The results show that refractive index sensitivity of this sensor is 506 nm/RIU, and the limit of detection for antihuman
IgG is 3 nM.
Microfluidic chip for spectroscopic and refractometric analysis
Show abstract
In this paper an optofluidic chip for simultaneous determination of refractive index and acquisition of absorption or
fluorescent spectra is described. The system comprises a microfluidic channel with multiple inlet/outlet for sample
handling and a dual fiber optic probe, standing face to face across the channel, for the optical measurements. An FBG
based Fabry Perot cavity, and a Braggmeter, allow for interferometric measurement of the refractive index while
external illumination and a multimode fiber enable acquisition of the absorption/fluorescence spectra with a CCD
spectrometer. Preliminary results showing the viability of simultaneous measurement are obtained from the
characterization of mixed samples with distinct refractive index and dye concentrations.
Fiber Grating Sensors
Understanding fiber Bragg gratings at harmonics of the Bragg wavelength through spectra and images
Show abstract
Fiber Bragg gratings written using a phase-mask exhibit a complex refractive index pattern in the fiber core,
as observed in differential interference contrast (DIC) microscopy. This results in dual periodicities along the
fiber core and gratings at both the Bragg wavelength, twice the Bragg wavelength, and the harmonics of these.
Features in grating spectra arise from one or both of these periodicities and spectra for twice the Bragg
wavelength (or its odd harmonics) are very sensitive to the details of how the UV complex diffraction field of
the phase mask becomes imprinted as refractive index changes in the fiber core.
Nanodiamond coated Bragg gratings for sensing applications
Show abstract
In this paper, the coating of optical Bragg gratings with nanocrystalline diamond, obtained by hot filament chemical
vapor deposition (HFCVD), is described. Due to the high temperature coating process, uniform fiber Bragg gratings
(FBG) were erased during the diamond deposition. However, in the case of regenerated fiber Bragg gratings (RFBG),
although attenuated, the optical signal is maintained. The results of the thermal and mechanical characterization of
diamond coated RFBG (D-RFBG) suggest that they may be an important tool in the sensing field, including monitoring
of high temperatures under harsh environments.
Hybrid BOTDA/FBG sensor for discrete dynamic and distributed static strain/temperature measurements
Show abstract
We propose and experimentally demonstrate a hybrid fiber optic sensing technique that effectively combines Brillouin
optical time-domain analysis and a time-domain multiplexing interrogation technique for Fiber Bragg Gratings (FBGs).
The highly-integrated proposed scheme employs broadband apodized low-reflectivity FBGs with a single optical source
and a shared receiver block, allowing for simultaneous measurements of distributed static and discrete dynamic
temperature and strain, over the same sensing fiber.
Two-dimensional fiber-optic vector vibroscope using only one multi-mode tilted fiber grating
Show abstract
Orientation-recognized two-dimensional vibration sensor based on a polarization-controlled cladding-to-core recoupling is demonstrated experimentally. A compact structure in which a short section of multi-mode fiber stub containing a weakly tilted fiber Bragg grating (TFBG) is spliced to another single-mode fiber without any lateral offset. Several well defined lower-order cladding resonances in reflection show different polarization dependence due to the tilted grating vector excitation. Both orientation and amplitude of the vibration can be determined unambiguously via dual-path power detection of the orthogonal-polarimetric odd-cladding-modes. Meanwhile, the unwanted power fluctuations and temperature perturbations can be definitely removed via core mode monitoring.
Multiplexed regenerated Fiber Bragg Gratings for high temperature measurement
Show abstract
High temperature gradient of a conventional tubular furnace is characterized using a single fiber sensing line with
wavelength-multiplexed short-length regenerated Fiber Bragg Gratings. The multiplexed gratings are simultaneously
regenerated using a high temperature annealing process. Temperature calibration from ambient temperature up to 850°C
is conducted leading to a standard deviation of 0.33°C after polynomial fitting of the wavelength shift with temperature.
Distributed Sensing II
Double-pulse Brillouin distributed optical fiber sensors: analytical model and experimental validation
Show abstract
An analytical model is presented to describe the behavior of the acoustic wave, probe signal and Brillouin gain in
double-pulse Brillouin optical time-domain analysis (DP-BOTDA) sensors. The proposed model is a tool that provides a
full physical insight into the Brillouin interaction occurring in this double-pulse configuration, and allows the
optimization and complete analysis of the system. The proposed solution is experimentally validated in a long-range
system, which is optimized to demonstrate experimentally, for the first time, the capability of DP-BOTDA to achieve a
11 km sensing distance with 20 cm spatial resolution and a frequency resolution of 0.5 MHz.
Dynamic BOTDA measurements using Brillouin phase-shift
Show abstract
We demonstrate a novel dynamic BOTDA sensor based, for the first time to our knowledge, on the use of the Brillouin
phase-shift instead of the conventional Brillouin gain. This provides the advantage of measurements that are largely
immune to variations in fiber attenuation or changes in pump pulse power. Furthermore, the optical detection deployed
can lead to an enhanced precision or measurement time and to the broadening of the measurement range.
Proof-of-concept experiments demonstrate 1.66 kHz measurement rate with 1-m resolution over a 160-m sensing fiber
length.
High sensitivity optical time-domain reflectometry based on Brillouin dynamic grating in polarization maintaining fiber
Show abstract
We newly propose and experimentally demonstrate high-sensitivity optical time-domain reflectometry based on
Brillouin dynamic grating in polarization maintaining fiber. Distributed measurements with strain sensitivity as high as
~ 1 MHz/με is demonstrated in a 110 m fiber under test with 0.8 m spatial resolution. The operation principle with the
condition for proper measurement of the grating spectrum and the advantageous features such as low operating power,
high signal to noise ratio, and simple data-acquisition process are explained in comparison with ordinary Brillouin
optical time-domain reflectometry, which is verified by the experimental results.
Towards fully distributed amplification and high-performance long-range distributed sensing based on random fiber laser
Show abstract
The random distributed feedback fiber laser (RDFB-FL), firstly proposed and demonstrated by S. K. Turitsyn et al.,
has been designated as the significant breakthrough in the fields of laser physics and nonlinear optics. In this paper,
the fully distributed Raman amplification approach, based on the novel concept of RDFB-FL, is proposed and
presented for the first time. As a typical proof-of-concept, the high-performance distributed sensing with ±1°C
temperature accuracy and ±2m spatial resolution, over entire 122km long-range Brillouin optical time-domain
analyzer (BOTDA), has been demonstrated using the fully distributed second-order Raman amplification based on
RDFB-FL proposed. The experimental results confirmed its unique ultra-low noise performance for the proposed
distributed amplification. We believe it's the best sensing result for such a length of BOTDA so far. The underlined
physical mechanisms associated with its quasi-lossless transmission and partial coherence characteristics, are also
presented, in order to account for this much attractive feature.
Synthesis of optical coherence function to sweep the 0th peak by phase modulation
Show abstract
We propose a method to shift whole the shape of synthesized optical coherence function along an optical path by phase
modulation. We can synthesize periodical delta function type optical coherence peaks by frequency modulation of a light
source to realize distributed measurement of back-scattering and/or reflections along an optical fiber by sweeping the
coherence peak as measurement window. In this study, we propose and demonstrate a method to synthesize and sweep
the 0th coherence peak by phase modulation with the same waveform as that for the laser frequency modulation. Basic
experiments of optical reflectometry are successfully demonstrated with the proposed method.
Interference-fading-free phase-demodulated OTDR system
Show abstract
A phase-shifted double pulse method is proposed to reduce the influence of inner-pulse interference induced fading on
phase demodulation of the Φ-OTDR. The feasibility of the technique is experimentally verified and the measurement
resolution of the Φ-OTDR is minimized to as low as 0.1rad by using this technique. The experimental system
demonstrates a distributed phase monitoring capability over 4km range with SNR of >20 and detection bandwidth
of >360Hz.
Sensor Application and Field Tests
Smart technical textiles based on fibre optic sensors
Show abstract
Smart technical textiles containing fiber optic sensors have been developed and successfully demonstrated for the
purposes of the structural health monitoring in geotechnical and civil engineering as well as for healthcare monitoring in
the medical sector. The paper highlights the results achieved in this innovative field in the framework of several German
and European projects and shows selected examples of using such fiber-sensor-based technical textiles in different
geotechnical and medical applications.
Field test of an in-well fiber laser geophone array
Show abstract
In this paper, we report the field test of a fiber laser geophone array. The field test is performed in a 3000 m depth well in
Liaohe Oil Field in northeast China. There are eight fiber laser geophones in the array with a space of ten meters. The
test results show good performance and reliability of the fiber laser geophone. This fiber laser seismic system is
promising in the in-well VSP system.
Region selectable gas sensing for long distance pipeline maintenance
Show abstract
We propose a region selectable gas sensing system, which can address gases of single and/or different species at multilocations.
This technique is based on optical spectroscopy of each selected numerous absorption lines of gas. Primary
experiment using fiber-optic absorption sensors, sensing regions and region selectors are demonstrated. Specific FBGs
are employed to reflect the selected spectrum for each sensing region. FBG monitor what encloses the tunable light
source and spectrum analyzer works as selected gas and region absorptions measurement. Absorption ratio was estimated
which indicates that the technique is applicable in lightweight fiber optic wide-regions gas sensing.
Distributed strain and load monitoring of 6 m composite wing structure by FBG arrays and long-length FBGs
Show abstract
We equipped a composite wing structure fiber Bragg grating (FBG) arrays including 246 FBGs with 10 mm gauge
length, eight and six long-length FBGs with 300 mm and 500 mm, respectively. The length of the wing was 6 m and it
was made of carbon fiber reinforced plastics (CFRP). The sensing system based on optical frequency domain
reflectometry (OFDR) was used in a series of load tests. The measured results by FBG arrays showed the overall
deformation of the wing and good agreement with analysis results. Additionally, strain distributions of stress
concentration zones were successfully measured by long-length FBGs.
Development of a discriminating fibre optic sensing array for wireless real time analysis of the maritime environment
Show abstract
In order to satisfy increasingly stringent maritime pollution control laws, it is necessary to develop sensors that are
capable of quantifying exactly the pollutants entering the marine environment. The development of an optical fibre based
sensor array suitable for the detection of known pollutants is discussed in this paper. The system being presented will
demonstrate how the incorporation of a novel fibre optic based sensor, with the ability to detect minute changes of
impurity in a liquid can be used on a Mote based platform in a real-time monitoring scenario and all for a relatively low
cost. [1]
Temperature sensing in a 175MW power generator
Cicero Martelli,
Erlon Vagner da Silva,
Kleiton de Morais Souza,
et al.
Show abstract
The surface temperature of a high power generator stator in operation at a hydroelectric power plant is measured using
fiber Bragg grating sensors. Insulation breakdown due to high voltage is a major problem in large electric generators and
very hard to detect at early stages. Giving the high temperatures that raise from this process the insulation degradation
can be detected as function of temperature. Fiber Bragg grating temperature sensors appear is a promising technology
since they can easily be embedded into the insulation with no harm for the generator.
Hybrid Brillouin-Rayleigh distributed sensing system
Kinzo Kishida,
C. H. Li,
Ken'ichi Nishiguchi,
et al.
Show abstract
The paper deals with the design and principles of the hybrid Brillouin-Rayleigh sensing system. The system is capable of
separating strain and temperature values in single SM fiber and offers spatial resolution as high as 2 cm. Furthermore,
the paper introduces a method to determine required separation coefficients for optical fiber cables. Finally, it presents
several validation examples and results of industrial applications.
Poster Session 1: Physical, Mechanical, Electromagnetic, and Fiber Grating
Development of an optical fiber transducer applied to the measurement of finger movements
Show abstract
A flexible and low-cost optical fiber transducer based on light attenuation by microbending was designed for the
measurement of angular displacements. The transducer was tested for predetermined rotations, presenting a higher
sensitivity for angles >10° by spacing the periodicity of the deformers by 2 mm. In addition, the performance on the
measurement of angles <10° was also enhanced by the specklegram analysis, yielding to a linear response. Furthermore,
the glove-mounted sensor was applied on the detection of the proximal interphalangeal joint, by performing the
calibration by artificial neural networks, resulting in calculated angle values compatible to the nominal ones.
Monitoring drying process of acrylic varnish with heterogeneous optical sensor
Fernando A. M. Saccon,
Fernanda M. D. R. de Oliveira,
Marcia Muller,
et al.
Show abstract
This work shows the application of a heterogeneous sensor system based on fiber Bragg gratings and optical coherence
tomography to monitor the drying process of a commercial water-based acrylic varnish. The varnish mechanical
deformation, thickness, and average refractive index developed in the process were monitored along 24 hours for a film
with approximately 430 μm of initial thickness, allowing identification of distinct time behaviors. Tomographic images
exhibited refractive index discontinuities along the total film thickness indicating the development not uniform and
concurrent through the whole material volume of the processes involved in the drying kinetics.
Intrinsic, multiplexable sensors for electric field strength using structural slow light in phase-shifted fibre Bragg gratings
Show abstract
In this paper we demonstrate through simulation the potential for phase-shifted fibre Bragg gratings incorporating
structural slow light to enable intrinsic reflection-mode point sensors for electric field or voltage. It is shown that lo-bi
FBGs incorporating multiple phase shifts yield large enhancements in group index (group delay) at resonance, thus
amplifying and localizing time-dependent non-reciprocal effects. A relative, multiplexable measurement of electric field
by comparison of the phase unbalance between linear modes on and off resonance is proposed, yielding static resolutions
of 24 V and 18 mV respectively in unpoled (dc Kerr effect) and poled (Pockels effect) fibres.
Multiplexing tapered optical fibres using coherent optical frequency domain reflectometry
Show abstract
Coherent optical frequency domain reflectometry is used to multiplex a serial array of tapered optical fibre sensors. By
monitoring changes in the Rayleigh backscattered signal from tapered regions of a single mode optical fibre, the
refractive index of the medium surrounding each taper can be determined. The approach is used to demonstrate a liquid
flow sensor.
High pressure discrimination based on optical fiber microsphere cavity Fizeau interferometer
Show abstract
Ahigh pressure sensor based on an optical fiber micro sphere cavity Fizeau interferometer (MSC-FI) is presented in this
paper.The sensorwas fabricated by use of a fusion splicer. The achieved pressure sensitivity of MSC-FI sensor was in the
range of 500 to 7000pi to be 4×10-4 nm/psi. With a 10 pm resolution for the wavelength shift detection, the resolution of
the device at room temperature for pressure measurement is to be 25 psi. This sensor can be used as a high pressure
sensor in downhole application.
Design and fabrication of SU-8 MEMS electrostatically tunable optical Fabry-Perot cavity based on photolithography technique
Show abstract
In this paper, we report a design and fabrication of MEMS electrostatically tunable Fabry-Perot (METFP) cavity sensor.
The mirror of METFP sensor is fabricated by SU-8 photoresist for the first time. The sensor is the combination of optical
fiber and microelectromechanical systems (MEMS) technologies. The voltage sensitivity of METFP is 0.036 nm/V and
the resolution of voltage measurement is 0.277 V.
Varifocal imaging using an ultrasonic optical lens with viscoelastic material
Show abstract
Varifocal imaging using an optical lens that employs acoustic radiation force and a viscoelastic material and that has no
mechanical moving parts is investigated. The lens has a simple and thin structure that consists of an annular ultrasonic
transducer and silicone gel. An axially symmetric acoustic standing wave can be generated in the gel by exciting a vibration
mode in the radial direction on the transducer. The lens profile can be altered by varying the acoustic radiation force of
the transducer. The focal length can be controlled by varying the transducer input voltage so that the lens functions as a
variable-focus lens.
Polarization-dependent bending sensor with temperature insensitivity
Show abstract
We propose the temperature-insensitive bending sensor based on a hole-assisted single polarization fiber (SPF). Without
fiber grating structures, the SPF-based sensing probe can provide the sensing technique to measure the bending change.
If bending is applied to the SPF, two cutoff wavelengths are shifted to shorter wavelengths and the transmission power is
diminished because the structural deformation of the SPF induced by bending changes birefringence depending on
principle axes of the SPF. However, the applied temperature variation has no effect on the birefringence change severely
and two cutoff wavelengths are not shifted by changing temperature. Therefore, the proposed SPF-based sensing probe
with temperature insensitivity can measure the bending change effectively.
Compact and high sensitivity curvature sensor based on twin core fiber coupler
Show abstract
A compact and high sensitivity curvature sensor based on twin core fiber (TCF) coupler is proposed and demonstrated
experimentally in the curvature range from 0 to 9.30 m-1. The TCF coupler is formed by splicing a section of 86.85 mm
TCF between two single mode fibers (SMFs). A nonlinear blue-shift of the wavelength was observed when increasing
the curvature. In the range from 3 m-1 to 9.30 m-1, the minimum and maximum sensitivity are - 2.5 nm/m-1 and - 14.7
nm/m-1, respectively. The dynamic range can be tailored by proper selection of the TCF length and the resonance dips.
Highly sensitive hydrostatic-pressure measurement with a fiber grating laser embedded in a composite structure
Show abstract
We present a high-sensitivity hydrostatic pressure sensor based on a dual-polarization fiber grating laser. To enhance the
sensitivity, the laser is embedded in a composite structure to effectively convert the pressure into intra-cavity
birefringence. The measurement is carried out by monitoring the beat frequency between the two orthogonal polarization
laser modes. The pressure sensitivity reaches 0.17 GHz/MPa within the range 0 to 10 MPa, about one hundred times
higher than the bare laser, and the minimal detectable pressure change is as small as 10 kPa.
A double-fiber F-P displacement sensor based on direct phase demodulation
Show abstract
To overcome the accuracy limits of fringe counting method for a F-P interferometer and the complexity of a higher
resolution demodulation system such as phase generated carrier (PGC), where a residual amplitude modulation always
exists in frequency modulation, this paper presents a fiber F-P displacement sensor based on double-interferometer phase
demodulation, which eliminates the modulation of lightsource. Comparing to the reported double-fiber F-P structure, our
design has no strict requirement for a specific phase difference between the two optical paths. Experimental results
demonstrate a good linearity of 1.1% and a resolution of ±3 μm within a measuring range of 0-0.5 mm.
A curvature sensor using a novel side-leakage photonic crystal fiber based Sagnac interferometer
Show abstract
A novel side-leakage PCF with high birefringence is designed and fabricated by introducing a linear side-leakage region
into both sides of the elliptical Ge-doped core. A curvature sensor using the homemade side-leakage PCF based Sagnac
interferometer is proposed and demonstrated experimentally. Experimental result shows that a high bending sensitivity
of 10.798nm/m-1 can be achieved when the linear side-leakage region is in the vertical with the direction of curvature.
With the measuring matrix obtained from sensor's sensitivity matrix by measuring the wavelength shifts of two dip in
the transmission spectrum, this sensor can also realize simultaneous measurement of curvature and temperature.
Characterization of longitudinal acoustic waves in a fiber using an extrinsic Fabry-Perot interferometer
Show abstract
Longitudinal acoustical modes propagating in a fiber are characterized using an extrinsic Fabry-Perot interferometer. The
method allows the detection of the fiber axial deflection peaks which correspond to the acoustic resonances. The method
can be further used for estimating properties of acoustic excited fibers, such as acoustic frequency and wavelength,
which are essential in the design of acousto-optic devices employing Bragg gratings.
Optical electric-field sensor using single β-BaB2O4 crystal
Show abstract
A novel optical electric-field sensor is proposed and experimentally investigated by using single beta barium borate (β-
BaB2O4, BBO) crystal. The optical sensing unit is only composed of single BBO crystal and two polarizers, the π/2
optical bias is provided by natural birefringence of the BBO crystal itself. Advantages of the BBO crystal over previous
lithium niobate crystal used as electric-field sensor mainly include larger measurement sensitivity and no ferroelectric
ringing effect. The 50Hz ac and lighting impulse electric fields in the range of (10~400)kV/m have been measured in
experiment with good linearity and fast response.
Temperature sensor based on fiber optic pyrometer in material removal processes
Show abstract
In this work, different non-contact fiber-optic pyrometers have been developed for measuring localized temperatures on
material removal area during mechanizing processes. Designs are developed for adaptation to the harsh measuring
conditions on specific cutting tool machinery and using commercial optoelectronics and fiber-optic components for
resolution enhancement. A 0.1 dB/°C sensitivity at 300 °C is obtained, and calibration curves at 1100 nm, 1300 nm, 1550
nm and 1610 nm are reported. Different reception circuits are used for testing resolution limits, higher bandwidths imply
greater noise and worst results as expected.
Simultaneous measurement of partial pressure of O2 and CO2 using hybrid interferometer
Show abstract
In this work, a hybrid interferometer for simultaneous measurement of the partial pressures of O2 and CO2 mixtures is
reported. The sensing head consist in two different interferometers based on a Fabry-Perot cavity and a modal
interference configuration. The intrinsic FP cavity was created by splicing a single mode fiber (SMF28) with a graded
index fiber section that was then subjected to chemical etching creating a cavity. The second interferometer is based on a
splice of a pure silica tube in series with the Fabry-Pérot. Due to the design, different sensitivities are achieved for the
pressure inducing refractive index changes of each gas. The rms deviations were found to be ± 0.079 kPa and ±
0.029 kPa for CO2 and O2 partial pressure measurements, respectively.
Interrogation system based on "figure-of-eight" fiber loop mirror
Show abstract
A theoretical and experimental study of a new fiber loop mirror based on a "figure-of-eight"configuration, is reported.
For the theoretical model, the Jones matrix analysis is analyzed. The configuration is tested as an interrogation system
where the spectral response arises from the combination of the reference signal modulated by the sensor signal. The
configuration is characterized in mechanical strain and presents a phase sensitivity of 8.2 mrad/με.
POF vibration sensor based on speckle pattern changes
Show abstract
A method of sensing vibration using detection of changes in the spatial distribution of energy on the speckle pattern in
the output multimode optical fiber is presented and demonstrated. The implementation of sensor consists of a small
length of fiber which is isolated and sensitive to ambient vibration. The projection of the speckle pattern is directly
recorded by a CCD camera at the outlet end of the fiber and processed changes in the intensity distribution. The sensor is
simple, inexpensive and can be implemented to measure vibrations in engine, machines or buildings.
Ambient index sensing technique using a Sagnac interferometer incorporating a tapered polarization-maintaining fiber
Show abstract
We propose a novel refractive index sensor using Sagnac loop interferometers configured by using tapered
polarization-maintaining fibers (PMFs) with different tapered diameters. To make the PMF sensitive to external
index change, a micro-tapering technique is exploited to fabricate the tapered PMF. The sensitivities of the PMFs to
ambient index strongly depend on the tapered diameters. The reduction of the PMF diameter results in the
enhancement of the ambient index sensitivity of the tapered-PMF-based Sagnac interferometer. However, the
temperature sensitivities of the proposed Sagnac interferometers are not changed by reducing the tapered diameters
of the PMFs.
A liquid level sensor based on fiber optic array and magnetic coupling
Wei He,
Xuan Yu,
Chenggang Wang,
et al.
Show abstract
A liquid level sensor based on fiber optic array and magnetic coupling is proposed and demonstrated. Besides the
inherent advantages of fiber optic sensor, this sensor has a feature of digital sensing signal since the accurate value of
light intensity is not needed, so the instability of light source, connecting and bending losses of optical fiber don't affect
the measurement results. Owing to its special structure and package, the sensor is insensitive to the fluctuation of liquid
level and could be used for measuring the level of almost all liquids regardless of their corrosivity and transparency.
Multi-monitoring system based on erbium doped fiber ring laser for measurement of radiation dose and strain
Show abstract
We propose a sensing scheme of an erbium-doped fiber (EDF) ring laser for multi-monitoring of radiation dose and
strain simultaneously. The EDF and fiber Bragg grating (FBG) are exploited as sensing probes for simultaneous
measurement of radiation dose and strain. The output power and the lasing wavelength of the proposed EDF laser are
changed by increasing the radiation dose and strain, respectively. The radiation and strain sensitivities were measured to
be 8.4 dB/km•Gy and 0.81 pm/με, respectively.
Embedded pressure sensor based on birefringent photonic crystal fiber
Show abstract
An embedded pressure sensor was made by sandwiching a polarization maintaining photonic crystal fiber (PM-PCF)
between two polymer foils. The excess birefringence induced by transverse pressure applied along the slow-axis of a
PM-PCF was numerically simulated with a finite element method. Experiment was carried out with a Sagnac
interferometer with the embedded PM-PCF as part of the Sagnac loop. The output interference fringes were found shift
linearly with applied transverse pressure with a wavelength to pressure sensitivity of 1.764 nm/MPa, The measurement
precision of 0.2%, and a dynamic range of 2.5 MPa were achieved.
Measurement of tunnel-ceiling and side-wall displacements using arc-shaped beam and fiber Bragg grating sensors
Show abstract
A method is presented for measuring the displacement of a tunnel's ceiling and side walls using arc-shaped beams and
fiber Bragg grating (FBG) sensors. The beams are installed inside the tunnel so that the displacements of the ceiling and
side walls are transferred to the beams. The displacements are computed using mechanical analysis of the strains they
produce on the surface of the beams. Table-top experiments demonstrated that the method is valid. This method can be
used to construct a system for monitoring the displacements in tunnels with various cross-sections.
Acoustic emission detection using a fiber laser array
Show abstract
In this paper we repot a novel acoustic emission detection method using a fiber laser array. The ultra-narrow line width
of the DFB fiber laser will result in a low equivalent noise level when using a fiber optic interferometric demodulation.
A minimum detectable strain of 10-12 is achieved in the experiment. Three fiber lasers are used in the array and the
acoustic emission is detected. The result is compared with that of a piezoelectric acoustic emission sensor.
Fiber optic push-pull accelerometer based on two cantilevers
Show abstract
In this paper a push-pull fiber optic accelerometer (FOA) is proposed. Using two cantilevers, the accelerometer operates
in a push-pull configuration. The sensitivity is analyzed based on the theory of elasticity; the frequency response is
analyzed based on the theory of vibration. Experiment is carried out to test the performance of the fiber optic
accelerometer. The experiment results agree well with the theoretical result.
High-sensitivity PCF sensing head for strain measurement
S. Rota-Rodrigo,
M. Bravo,
A. M. R. Pinto,
et al.
Show abstract
An original photonic crystal fiber based sensing head is proposed for strain measurement. The sensor comprises a Hi-Bi
PCF sensing head to measure in reflection using polarimetry. A background study of the sensing head polarization state
signals is conducted utilizing an optical backscatter reflectometer. Using a more accessible set up, one of the Hi-Bi PCF
polarization signals is isolated allowing to accurately measure strain variations. In-reflection polarimetric strain sensing
is obtained with a sensitivity of ~7.6 dB/1000μm and with the breakage point at 5500 με.
New spatial optical filters for gas refractometry
Show abstract
A spatial optical filter based on splice misalignment between optical fibers with different cladding dimensions is
proposed for gas refractometry. The sensing head is formed by a 2 mm-long optical fiber with 50 μm diameter spliced
with a strong misalignment between two single mode fibers (SMF28) and interrogated in transmission. This fiber
structure causes a Fabry-Pérot-behavior along the reduced-size fiber giving at its output end a well defined spatial
filtering selectivity. Depending on the misalignment position of the lead-out SMF28, it is possible to obtain two different
spectral responses, namely, bandpass or band-rejection filters. It is shown that this filter device is highly sensitive to
refractive index changes on a nitrogen (N2) environment by means of the gas pressure variation. A maximum sensitivity
of -1390 nm/RIU for the bandpass filter was achieved.
Sensitivity characteristics of high-birefringence Sagnac interferometer sensors
Show abstract
The sensitivity characteristics of the sensors based on high-birefringence Sagnac interferometer are theoretically
analyzed and experimentally verified. We analyze the sensitivity of the sensor in terms of the frequency instead of the
wavelength of the light and the sensitivity can be improved by reducing the length of high birefringence fiber. The strain
sensing experiments are carried out and the experimental results agree well with the theoretical analysis.
A weak feedback effect based fiber laser sensor demodulated by a phase generated carrier scheme
Show abstract
We propose a weak feedback effect based fiber laser sensor demodulated by a phase generated carrier (PGC) scheme.
The weak feedback, realized by an optical fiber pigtail with a fiber end-face, couples a small part of light back to the
fiber laser cavity to realize the light intensity modulation of the fiber laser. The sensor system based on the PGC
demodulation scheme avoided the signal fading, caused by out of quadrature, and realizes the reliable vibration
measurement.
Development of a polarimetric vibration sensor for quasi-distributed measurements
Show abstract
In this paper we propose a novel kind of quasi-distributed polarimetric vibration sensor. Its functioning is based on the
use of mechanical transducers, which transform the mechanical vibration into a birefringence variation, and of fiber
Bragg gratings (FBGs), which reflect light from different positions. As it will be shown this sensor can provide the
vibration frequency in a quasi-distributed manner.
Multimode interference in tapered single mode-multimode-single mode fiber structures for strain sensing applications
Show abstract
Tapering single mode-multimode-single mode structures to enhance sensitivity is proposed and experimentally
demonstrated. 50 mm-long coreless MMF sections are spliced between SMFs and tapered. They are characterized in
strain and an increase in strain sensitivity is obtained with taper diameter reduction. Sensitivities as high as -23.69 pm/με
for the 15 μm taper are attained. A combination of an untapered and tapered SMS is proposed as a sensing system for the
simultaneous measurement of strain and temperature.
Magnetic field sensor with Terfenol-D thin-film coated FBG
Ricardo M. Silva,
G. Chesini,
C. J. Gouveia,
et al.
Show abstract
In this work a magnetic field sensor based on an FBG coated with a thin film of Terfenol-D is presented. The sensor was
tested with two optical interrogation systems: one, a scanning laser system with a 1 pm resolution, and the other a
differential white light interferometer (WLI). The results obtained in the magnetic field range of 20 mT to 100 mT, show
the possibility of increasing the magnetic field measurement resolution, with temperature fluctuations invariance, by a
factor of 4.5 when using the WLI system.
Unbalanced nulling interferometer with four-quadrant phase mask
Show abstract
One of the problems for direct observation of extrasolar planets is the speckle noise due to a wave-front error.
Therefore, high-accuracy adaptive optics is required for realizing a wavefront quality of λ/10000 rms. An unbalanced
nulling interferometer has a possibility to assist high-accuracy correction. In this paper, we propose the interferometer
with a four-quadrant phase mask in which an optical path is common. By using the mask, we succeed in stabilizing the
interference and taking measurements of wavefront errors with 10-times higher sensitivity. In this way, we expect to
construct high-accuracy adaptive optics which is more stable.
Towed vector fiber optic sensor used in ocean seismic exploration
Wei Rao,
Yongming Hu,
Zhengliang Hu,
et al.
Show abstract
In order to overcome the drawbacks of the pressure sensor in ocean seismic exploration, we try to use the towed
vector fiber optic sensor (VFOS) array for the application of ocean seismic exploration. The VFOS with three fiber optic
accelerometers outperforms the pressure sensor in dynamic range and quality of the reflected wave. A real VFOS array is
developed and tested in Lake Trail. Results illustrate that the data from the VFOS construct more distinct stratum layers
than the pressure-sensing fiber optic hydrophone.
Integration of ultralow-noise single-frequency lasers with extrinsic seismic sensors using optical transducers
Show abstract
The results of high-performance seismic sensors using advanced ultralow-noise single-frequency lasers are
presented. We have developed a family of vibration sensors that are based on extrinsic optical Fabry-Perot
cavities, and provide many advantages compared with other types of sensors, including conventional fiber
sensors and electromagnetic sensors. These novel sensors offer substantial reduction in size and cost, while
still providing competitive performance. Size reduction also means an effective reduction in deployment
cost, which is very important in the remote areas where seismic sensor arrays are needed.
Conventional optical fiber current measurements improved by a high accuracy artificial neural network algorithm
Antonio C. Zimmermann,
Marcio Besen,
Leonardo S. Encinas,
et al.
Show abstract
This paper relies on an experiment using a conventional fiber optical current measurement system with new concept for
signal processing using Artificial Neural Networks. To achieve the high accuracy results, a class 0.1% current standard
was used as reference for the ANN processing. Also a large data collection was conducted to assure the high variability
of the measurement process behavior, including changes in temperature and other non-linear effects. The results show
0.2% maximum error for the developed system, demonstrating the robustness and high accuracy of the proposed method,
being capable of mitigate some drawbacks of FOCS system, like non-idealities compensation.
Optical bidirectional force sensor using optical planar waveguide
Show abstract
We demonstrate an optical planar waveguide sensor that can be used to measure the direction and intensity of
physical force. The interferometric structure, on which the proposed sensor is based, introduces an interference
pattern in wavelength. Its phase is shifted by the external force. On the other hand, since the cross-sectional effective
refractive index profile is asymmetric because of the core formed on one side of silica substrate, the phase shift
appears with respect to the direction of the external force against the surface. Therefore, we can measure the
direction and intensity of the applied force by monitoring the phase change.
Fiber optic bend and temperature sensing in femtosecond laser-structured POF
Show abstract
We propose focused femtosecond laser irradiation to create stable and permanent scattering damage in large-core
polymer optical fibers. Possible sensing applications using optical time domain reflectometry are discussed and
presented. Experiments show that quasi-distributed fiber bend sensors and absolute temperature sensors can be realized
by evaluating backscatter intensities.
The characteristics of DFB fiber laser with weak feedback
Show abstract
We investigate the weak feedback effect for Distributed Feedback fiber lasers (DFB FL) experiencing Rayleigh backscattering
and the reflection end facet from single mode fiber length of 200 m. We also use that configuration as a sensor scheme for acoustic and vibration measurements.
Sensitivity analysis and temperature performance of the fiber Bragg grating (FBG) acceleration sensor
Show abstract
A high sensitive fiber Bragg grating (FBG) acceleration sensor based on filtering demodulation is analyzed on
sensitivity, resolution and temperature experiment. Sensitivity and resolution of FBG sensor lies on the structure of the
sensor shell and the shape of the reflectivity spectrum of FBG. The temperature experiments of the FBG sensor show the
work and storing temperature range of the sensor based on different preparing stress and packaging glue. Experiments on
the detecting system's frequency character have been done. Results show that this acceleration sensor can detect the
smallest acceleration of 1mm/s2 with a flat response from 5Hz to 40Hz.
Toward track component condition monitoring using optical fibre Bragg grating sensors
Show abstract
Optical fibre Bragg grating sensors have been field-trialed for the monitoring of dynamic loading of fish-plates, stretcher
bars and switchblades on a tram network, with the aim of developing a condition monitoring system. This paper provides
preliminary data showing the ability to identify changes in track/component condition.
Design of a fiber Bragg grating sensor interrogation system using volume phase grating and CCD detection
Show abstract
The design of a portable FBG Interrogation System is presented in this paper. By using volume holographic phase
grating as the dispersion spectral element, the interrogator achieves 5 KHz scanning frequency with a readout
wavelength resolution of 1 pm. The total power consumption is less than 25 W.
An integrated polarization-holding fiber polarizing grating based on side-polishing and metal film coating techniques
Lina Ma,
Nuan Jiang,
Huizu Lin,
et al.
Show abstract
Optical fiber polarizer and grating are two widely used fiber components and in this paper we proposed an integrated
polarizing grating fabricated in polarization-holding fiber, which achieves reflecting and polarizing functions
simultaneously. A D-shaped multilayer grating waveguide model was established and the linearly polarizing principles
in both reflection and transmission ports were presented. An integrated polarization-holding fiber polarizing grating was
fabricated and the laser polarization states of incidence, reflection and transmission were all measured, showing that this
integrated fiber device can achieve reflecting and polarizing functions simultaneously. The discrimination between the
reflection and transmission was also investigated.
Strain measurement inside a strong pulsed magnet based on embedded fiber Bragg gratings
Show abstract
The measurement method of strain inside strong pulsed magnet has been demonstrated by using embedded fiber Bragg
gratings. 23 FBGs were embedded in a strong pulsed magnet of 60 Tesla. The strain inside the magnet was successfully
measured in a 10-millisecond pulse time by adopting high speed demodulation devices in normal temperature and liquid
nitrogen temperature, respectively. The research achievement is significant for the further development of strong pulsed
magnetic field technology.
Ultrasonic frequency response of surface attached fiber Bragg grating
Show abstract
The spectrum shift of FBG to ultrasonic wave is caused by the refractive index profile changing along the FBG, which
can be attributed to nonuniform perturbation caused by strain-optic and geometric effects of ultrasonic wave. Response
of FBG to the above two effects was analyzed by V-I transmission matrix model, showing high computing efficiency.
Spectra response of FBG under changing ultrasonic frequencies was simulated and discussed. In experiment, the system
was sensitive enough to detect ultrasonic wave from 15 kHz to 1380 kHz. These results would provide a guideline for
FBG-based acoustic detection system design in a specific ultrasonic frequency.
Optical fiber sensing with chirped FBG Fabry-Perot interferometer: vibration measurement
Show abstract
A Fabry-Perot interferometer with chirped FBGs as reflectors has hundreds of resonance peeks in the transmittance
spectrum and can be utilized as a sensor based on the dependency of the peak wavelengths on the influence applied to
the fiber. Because the width of the peak is narrow and the number of the peak is large, one may well expect high
resolution and/or large dynamic range in its operation. In this paper, we propose to use it for measuring vibration of solid.
We characterize the sensor for two kinds of interrogation methods: the intensity-modulation and wavelength-sweep
schemes. The sensor works well and the former scheme yields a lower minimum detectable strain while the latter gives
flexibility in the magnitude of the dynamic range. In addition, difference in finesse between shorter- and longerwavelength
regions allows us to design a sensor of different sensitivity by changing the operation wavelength.
Development of micro-tapered long-period fiber gratings written in tapered fibers with different diameters for enhancement of strain sensitivity
Show abstract
Micro-tapered long-period fiber gratings (MT-LPFGs) written in tapered fibers with different diameters of 125, 100, 75,
and 50 μm are fabricated and their transmission characteristics with variations in strain and temperature are investigated.
Since the variation of the refractive index with the applied strain change is inversely proportional to the cross section
area of the MT-LPFGs, the strain sensitivity of the MT-LPFGs is further improved. The temperature sensitivity is also
enhanced by reducing the diameter of the tapered fiber. The experimental results are very useful for discrimination of
strain and temperature sensitivities.
Enhanced sensitivity of gold modified tapered long period fiber grating for refractive index measurement
Show abstract
In this work, a novel approach to application of tapered long period fiber grating (TLPFG) sensor is demonstrated, which
are based on the modification of gold nanoparticles (GNPs). The sensor we propose here is a TLPFG fabricated with
CO2 laser by heat-pulling method. TLPFG was immobilized with GNP and its refractive index sensitivity was measured.
Experimental results show that modification of the TLPFG with GNPs enhances the evanescent wave and penetration
depth around the sensor. Comparing different resonance dips of gold modified and bare TLPFG, improvement of 10.3
and 6.6 times can be estimated for wavelength and intensity sensitivities, respectively.
Long distance fiber Bragg grating strain sensor interrogation using high speed Raman-based Fourier domain mode-locked fiber laser with recycled residual Raman pump
Show abstract
We propose a novel fiber Bragg grating (FBG) sensor interrogation system using a Raman-based Fourier domain mode
locking (FDML) fiber laser for a high speed and a long distance measurement. To improve transmission efficiency of the
sensing probe signal over a long distance of 20-km, the residual pump powers are recycled. The external strain change
can be measured by detecting the tine interval between two reflected signals from two FBGs as the Rama-based FDML
is swept. The measured strain sensitivities with respect to the time are 0.19 ns/μstrain.
Metal packaged fiber Bragg grating accelerometer
Show abstract
A metal packed fiber Bragg gratings accelerometer has been proposed. Copper was adopted to cover the surface of
optical fiber by magnetron sputtering and electroplating technology, and then tin soldering was used to fix the metalized
fiber on mass and foundation. Because of copper coating and soldering, the elastic coefficient and ductility of FBGs have
been increased, and the problems of aging and creep arising from polymer or adhesive packaged have been avoided.
Experiment result demonstrated that the accelerometer possess of a resonant frequency of 2800Hz, a wide linear
measurement range from 0.5g to 5.3g and a sensitivity of 84mv/g.
A miniature fiber Bragg grating pressure sensor for in-vivo sensing applications
Show abstract
A miniature FBG pressure sensor is reported. Two optical fibers containing FBG arrays are twisted together and the
sensing elements are enclosed in a specially designed structure to detect variations in the ambient pressure. It provides an
overall diameter of ~1 mm which is extremely beneficial for the studies of peristalsis in the gastrointestinal tract and
flow in the vascular system. The static and dynamic responses of the miniature catheter were calibrated and the results
are presented.
Distributed monitoring of fiber Bragg gratings under local lateral loads using optical frequency domain reflectometry
Show abstract
We demonstrate distributed monitoring of long-length fiber Bragg gratings (FBGs) under lateral loads using optical
frequency domain reflectometry (OFDR). Local lateral loads are applied to a certain area of the long-length FBGs. We
observe splits of Bragg peaks due to the lateral loads in a distributed manner. We calculated the lateral loads based on the
amount of Bragg peak splits, which showed the good agreement with the applied loads.
Intensity-based LPG vibration sensor array using FBG and broadband optical source
Show abstract
A novel fiber optic sensor array is proposed and demonstrated by multiplexing intensity-based long-period fiber grating
(LPG) sensors, in which a simultaneous multipoint detection of mechanical vibrations as well as a highly sensitive
operation is realized. In the intensity-based detection scheme, multiple narrowband light sources are provided by use of
a broadband amplified spontaneous emission (ASE) source and fiber Bragg gratings (FBGs) with their wavelengths
adjusted to the spectral dips of the sensing LPGs. The LPG vibration sensor array is achieved by using a combination of
wavelength division multiplexing (WDM) and space division multiplexing (SDM) technique. In the experiment, the
LPG sensor array is constructed by multiplexing two LPG sensors in tandem and simultaneous multipoint vibration
detection without crosstalk is successfully demonstrated.
Tunable narrow-band source using a VCSEL and an EDFA for interrogation of fiber Bragg grating sensors
Show abstract
Wavelength tuning with a current of a long-wavelength vertical-cavity surface-emitting laser (VCSEL) with a spectral
line width of 30 MHz was studied. To stabilize the power, saturated amplification of the VCSEL output by an erbiumdoped
fiber amplifier (EDFA) was performed. For wavelength tuning by 2.5 nm, there was a 3-fold change in the
VCSEL output power; however, the variation in the amplified output power was within ±13%. For wavelength tuning of
4 nm, the variation was ±20%. Application to fiber Bragg grating sensor interrogation was discussed.
Micro-ridge long-period fiber gratings inscribed on a polarization-maintaining fiber for measurement of strain
Show abstract
Micro-ridge long-period fiber gratings (MRLPFGs) inscribed on a polarization-maintaining fiber (PMF) were
demonstrated. The cladding region of the PMFs was periodically etched by using a wet etching technique, resulting in
the periodic micro-ridges in the surface of the PMF. The PMF-based MRLPFGs has two resonant peaks because of the
birefringence of the PMF. Two resonant peaks of the PMF-based MRLPFGs were generated by increasing the applied
strain because of the photoelastic effect. The peak depth is only changed by increasing the external strain. It means that
the proposed PMF-based MFLPFGs are very useful for the application to strain sensors.
Optical fibre gratings with response to 2µm and their sensing capabilities
Show abstract
Recently, we have extended fibre grating devices in to mid-IR range. Fibre Bragg gratings (FBGs) and long-period
gratings (LPGs) with spectral responses from near-IR (800nm) to mid-IR ( ~ 2μm) have been demonstrated with
transmission loss as strong as 10-20dB. 2μm FBG and LPG showed temperature and refractive index (RI) sensitivities
of ~ 91pm/°C and 357nm/RIU respectively. Finally, we have performed a bio sensing experiment by monitoring the
degradation of foetal bovine serum at room temperature. The results encouragingly show that the mid-IR LPGs can be an
ideal biosensor platform as they have high RI sensitivity and can be used to detect concentration change of bio- samples.
Detecting mode hopping in fiber ring lasers by anisotropic dynamic gratings
Show abstract
We have demonstrated that a polarization-insensitive anisotropic dynamic grating can be used to detect accident
mode hopping in long-cavity-length fiber ring lasers. The polarization-insensitive property of the grating is realized by a
Faraday rotator mirror and validated experimentally. The mode hopping properties of a particular single-longitudinalmode
erbium-doped fiber ring laser is examined by an anisotropic grating with 3-m long erbium doped fiber. When
mode hopping occurs, the grating responds a negative intensity peak. Repeated measurement shows that the continuing
cavity length wandering during the laser operation is the origin of the accident mode hopping when there is no
modulation applied to the cavity length.
Ultra-long distance fiber Bragg grating sensor system based on self-heterodyne detection
Jiangjiang Cai,
Guoliang Xu,
Xiaodong Zhao
Show abstract
A long-distance fiber Bragg grating (FBG) sensor system based on the self-heterodyne detection technique is
proposed and experimentally demonstrated. In this system, a wavelength tunable laser was employed to scan the
reflection spectrum of the FBG, and the reflection sensing signal was separated from the Rayleigh backscattering
effectively. The system can achieve 148 km measurement length without amplification and the signal-noise ratio (SNR)
of the detected Bragg wavelength signal is up to 24 dB. Applying this system to remote temperature detection, the
measurement accuracy is 1°C.
The fiber-optic displacement sensor based on the DBR fiber laser
Show abstract
The fiber-optic displacement sensor based on the distributed Bragg reflector fiber laser is proposed, that is, the fiber laser
cavity is attached to the measured object, when the measured object is stretched or contracted, and the length of the fiber
laser cavity is changing too. In view of nonlinearity of the fiber-optic displacement sensor, the calibration based on
piezoelectric ceramics is applied to improve the linearity of the displacement sensor. Experiment results show that the
fiber-optic displacement sensor has a linear response with the nominal working distance of 90 μm. Furthermore, the
fiber-optic displacement sensor may realize the dynamic measurement.
Comparison between PMMA and PVAC coated fiber Bragg grating sensors for relative humidity measurements
Show abstract
The paper reports some preliminary results obtained on two polymer-coated fiber Bragg grating based humidity sensors
fabricated using poly(methyl methacrylate) (PMMA) or poly(vinyl acetate) (PVAc) as sensing material. The calibration
of the two sensors has been carried out in the 20 - 70 %RH range at three different temperatures (15, 30 and 45°C) using
a two-pressure humidity generator. Repeatability and time response were assessed by means of multiple reversible RH
step inputs. The PMMA-coated sensor prototype displayed overall much better performance when compared to the
PVAc-coated one, although it manifested a somewhat higher temperature sensitivity.
High multiplexing capability and ultrahigh resolution interrogation for optical fiber Bragg grating sensing system
Show abstract
A high multiplexing capability and ultrahigh resolution interrogation scheme for optical fiber Bragg grating sensing
system was proposed. A scan ring laser based on semiconductor optical amplifier (SOA) and tunable Fabry-Perot
interferometer can provide 70nm bandwidth and 32 monitoring channels, and therefore the interrogator can
simultaneously detect more than 1000 fiber Bragg grating (FBG) sensors. In the interrogation scheme, a gas absorption
spectral line was used as a wavelength reference, and a comb filter was designed as a standard device that can
dynamically calibrate the wavelength of FBG sensors. Therefore, the wavelength resolution can reach to 0.5 pm.
High alternating current sensor based on FBGs and magnetic coupling
Show abstract
In this paper, a novel Fiber Bragg gratings (FBGs) high alternating current sensor is proposed to measure alternating
current. The principle and sensing structure are introduced. The sensitivity of the high alternating current sensor is
13.8pm/A when the current is 1000A. The trend shows a good linearity between the wavelength shift and the square of
the current value which is consistent well with the principle and indicates that the proposed sensor is capable of
measuring high alternating current.
Based on fiber grating the high sensitivity all optical fiber CTD
Show abstract
We designed and manufactured all optical fiber CTD to monitor ocean based on the sensitive characteristics about
optical fiber grating. A series of works have done, including the calibration work for sensor in laboratory, simulated
experiment outside and the local test of ocean parameter. The results we got show that the precision of temperature is
0.01℃ and of pressure is better than 0.1%, both of them overtake the secondary standard of GB/T23246-2009, moreover,
close to the primary standard, and of salinity in laboratory has reached 708 pm/1% closely to the secondary standard. It is
satisfied with the ocean monitoring requirements.
Remote sensing based on reflective bandpass long-period fiber grating and fiber ring laser
Show abstract
A remote sensing system based on bandpass long-period fiber grating (LPFG) and fiber ring laser is proposed in this
paper. The reflective bandpass LPFG is fabricated by fusion splicing a piece of hollow core fiber (HCF) to the LPFG.
And the fiber ring laser is employed to narrow the line-width of the bandpass LPFG and realize remote sensing. As an
application example, a temperature experiment is conducted at the spot more than 1 km away from the fiber ring laser.
The experimental results show that such a sensor has a sensitivity of 0.0254nm/°C within the range of 20-150°C.
Enhanced axial strain sensitivity in plasmonic tilted fiber Bragg gratings sensors
Show abstract
This paper experimentally analyses the axial strain sensitivity of gold-coated tilted fiber Bragg gratings immersed in
liquid. For the polarization mode P (polarization parallel to the tilt plane), a strong attenuation of some cladding mode
resonances appears in the transmitted spectrum due to the coupling with the Plasmon wave. When axially straining the
grating, we report a unique behavior for the cladding mode resonance that presents the strongest attenuation. It presents
an axial strain sensitivity (1.33 pm/με) higher than the Bragg wavelength (1.28 pm/με) and much higher than
neighboring cladding modes (1.16 to 1.22 pm/με), meaning that differential strain measurements can be achieved with
such a sensing platform.
Simultaneous measurement of refractive index and temperature based on a partial cone-shaped FBG
Liang Qi,
Chun-Liu Zhao,
Shuqin Zhang,
et al.
Show abstract
A refractive index and temperature simultaneous measurement sensor based on a partial cone-shaped fiber Bragg grating
(FBG) was demonstrated. The bandwidth of the partial cone-shaped FBG is only effected by the surround refractive
index (SRI), while the wavelength decided by the un-etched FBG is only sensitive to temperature. Utilizing the obvious
difference of the bandwidth and the wavelength on temperature and the refractive index, two parameters can be
distinguished and measured simultaneously using one partial cone-shaped FBG. Experimental results show that the
proposed sensor has a SRI sensitivity of -13.669 nm/RIU in the range of 1.33~1.42 and a temperature sensitivity of 9.8
pm/°C in the range of 20~80°C.
Fiber-optic thermal anemometer based on metallic coated fiber Bragg grating
Show abstract
A novel thermal anemometer based on a core offset single-mode fiber (SMF) combined with a fiber Bragg grating (FBG)
coated with silver film is proposed. Light from a pump laser at 1450 nm propagating down the fiber is coupled by the
offset into the fiber cladding. A silver coating was deposited on the fiber surface over the Bragg grating structure to
absorb the light. As a result, the dynamic thermal equilibrium would be reached between the laser heating and air flow
cooling by monitoring the FBG's wavelength shift. Experimental results reveal that the Bragg wavelength shift is related
to the flow velocity and the highest resolution of the thermal anemometer is about 0.05 m/s in the range of 0-17.31 m/s.
Dual-peak wide range temperature LPG sensor fabricated with a CO2 Laser and a high resolution system
Show abstract
In this work we present a specially designed high resolution electromechanical system to be used with a cw CO2 Laser to
fabricate high quality long period grating sensors (LPG). We also describe the experiments carried out to measure the
resulting enhanced transmission spectra of the fabricated LPG and to measure their response as temperature sensors.
Sharp and well pronounced spectral peaks were obtained reaching 30dB. Sensitivity values of 118 pm/°C were easily
obtained without any fiber coating. Wide range temperature coverage (20 - 600 °C) was attained by making use of two
distinctive peaks of the transmission spectrum.
Pipe flow speed sensor based on fiber Bragg gratings
Show abstract
A fluid flow speed sensor based on Fiber Bragg Gratings (FBGs) is proposed and demonstrated. Two
FBGs are attached to an arc-shaped plastic piece at the same distance from both edges. The fluid flow to
be measured pushes the structure stretching one side and compressing the other one. The sensor has been
successfully checked by subjecting the device, to different air flow controlled conditions inside of a pipe.
Low energy impact detection has been also reported with the proposed device.
Determination of chewing patterns in goats using fiber Bragg gratings
C. Wosniak,
W. J. Silva,
R. Cardoso,
et al.
Show abstract
This paper describes experimental procedures with a goat cadaveric skull aiming the identification of patterns during the chewing process, simulated with two plasticines having different textures. Fiber Bragg Gratings (FBG) are used to monitor the biomechanical forces related to the chewing process, whereas the obtained signals were processed by neural networks, in order to classify and recognize the presence of different plasticines in the chewing process.
Dual-polarization DBR fiber laser sensor for liquid-level measurement
Show abstract
A dual-polarization distributed Bragg reflector (DBR) fiber grating laser for liquid level measurement is proposed and
experimentally demonstrated. The laser cavity is used as the sensing device. The liquid level is obtained by measuring
the beat frequency generated between the two lasing polarizaion modes. The result shows the beat frequency shifts
linearly with the water level and a sensitivity of 241 kHz/mm has been obtained. The sensor is simple, easy to fabricate
and with high sensitivity to liquid level variation, which could be very helpful in practical applications.
Novel acoustic emission sensor system based on two cascaded phase-shifted fiber Bragg gratings
Show abstract
A novel acoustic emission (AE) sensor system based on fiber Bragg grating is proposed. Two identical phase-shifted
FBGs (PS-FBGs) are cascaded after an amplified spontaneous emission (ASE) source, used as filter and sensor
respectively. By measuring the change of the output power, the AE signal and low frequency vibration can be detected.
Because of the sharp peak in the middle of the PS-FBG spectrum due to the phase shift, the sensitivity of the system is
guaranteed while preventing the photo-detector from saturation. The proposed system has the advantages of simple
configuration, no-resonance, electromagnetic interference immunity and low cost.
Refractive index sensor employing PVA-coated long period grating technology
Show abstract
The sensitivity of a Long Period Grating (LPG)-based refractive index (RI) sensor has been enhanced through an
appropriate coating of a thin polymer layer, with a higher RI than that of the cladding, on the LPG. The performance of
the coated sensor, together with a bare LPG, was evaluated as a chemical sensor when the sodium chloride concentration
in water varies from 0.01% to 2%. The corresponding attenuation band shifts of both sensors in response to the RI
change were observed. The experimental results confirmed that the coated LPG sensor has higher sensitivity than that of
the bare LPG sensor.
Gap FBG and its application in tunable narrow linewidth fiber laser
Show abstract
A gap fiber Bragg grating (g-FBG) is fabricated by cutting a uniform FBG in the middle to introduce a small air gap
between the two sections. Numerical and experimental investigations show that the g-FBG has the characteristics of both
a phase shifted FBG and a Fizeau interferometer. The peak transmission wavelength of the g-FBG can be tuned by
adjusting the air-gap longitudinally or transversely with respect to the fiber center-axis. With a g-FBG as tunable
intra-cavity filter, a tunable fiber ring laser with a narrow line-width is demonstrated. The wavelength tuning range of the
laser is 0.12 nm with a output power flatness better than 0.9 dB. The 3 dB spectral line-width is less than 12 pm and
output power is 3.68 dBm.
Thickness influence on the polarization dependency of tilted fiber Bragg gratings coated by zinc oxide thin films
Show abstract
Tilted fiber Bragg gratings (TFBGs) transmitted amplitude spectra intrinsically depend on light polarization, leading to
the existence of two peak families separated by a few picometers to a few tens of picometers for the s and p-polarized
light states. In this paper, we demonstrate that, thanks to a dense thin film with high refractive index (Zinc oxide)
deposited around TFBGs, the polarization dependency can be drastically enhanced, resulting in a wavelength separation
of up to 550 picometers between the two orthogonal resonance peak families. This results in two important assets: the
sensitivity is extended to surrounding refractive index (SRI) values above 1.45 while the strong polarization dependency
makes the demodulation process easier with differential SRI sensitivities between the two modes families.
Effect of high temperature on the properties of long-period gratings written in non-hydrogenated fibers with UV and electric arc
Show abstract
This work presents the effect of high temperature (~350°C) on the performance of the LPGs written in non-hydrogenated
standard fiber (Corning SMF28) and in photosensitive fibers (Fibercore PS1250/1500 and Nufern GF1) using UV
exposure and electric arc discharge. The effect is discussed from a point of view of application of the gratings as
platforms for high-temperature overlay deposition to enhance sensing properties of such LPGs. Our experiment shows
that only arc-induced gratings are suitable for high-temperature coating deposition and high temperature processing up to
350°C. It is shown that the temperature induced degradation effect for UV-written LPGs does not depend on composition
of the core of the fiber and takes place for both photosensitive fibers. Moreover, for the LPG written in GF1 fiber the
spectrum does not shift when the sample is cooled down, but stays the same as it was at the higher temperature.
Performance comparison of fiber Bragg gratings sensor interrogation using two kinds of wavelength-swept lasers
Show abstract
We report a performance comparison of fiber Bragg gratings (FBGs) sensor interrogation using two kinds of
wavelength swept lasers. In a wavelength swept laser with a fiber Fabry-Perot tunable filter (FFP-TF), the reflected
signal from the FBGs in temporal domain has a nonlinear response with respect to the sinusoidal modulation signal. The
output of the time delay for the strained FBGs sensor array in the wavelength swept laser with FFP-TF has different
slope coefficient for each FBGs, while the reflected output of the strained FBGs in the wavelength swept laser with
polygon scanning filter has same slope coefficient for each FBGs.
Nonlinear response in polymer optical fibre Bragg grating based sensors
Show abstract
PMMA based polymer optical fibre Bragg gratings have been used for humidity, temperature and concentration sensing.
Due to the water affinity of PMMA, the characteristic wavelength of the grating is largely modulated by the water
content in the fibre. The rate of water transportation between fibre and surrounding depends on the permeability
coefficient for PMMA, which is a function of surrounding temperature and humidity. This leads to increased water
content with increasing humidity and temperature. Consequently the wavelength of the grating shows a nonlinear change
over varying humidity and temperature. This nonlinearity needs to be calibrated prior to sensor application.
Strain response of POF sensors
Show abstract
With regard to polymer fibre Bragg gratings, we investigate one of the consequences of the visco-elastic nature of the
constituent polymer: hysteresis in the response of wavelength shift vs sensor elongation. We show that when a grating
sensor is directly bonded to a substrate, the hysteresis is reduced by a factor of 10 from the case where the sensor is
freely suspended between two supports.
Temperature level optical fiber sensor using shape memory alloy wires
Show abstract
A temperature Level fiber Optic transducer based on a fiber grating-shape Memory Alloy wire structure (LOMA) is
presented in this paper. The basic sensors system works as an on/off optical device: only output light is offered by the
device when the structure temperature (T) is over a given temperature level (T>TL). The proposed fiber structure can be
used as point or as quasi-distributed sensors systems exploiting its optical multiplexing capacities. The simple and cost
effective device is successfully demonstrated in the laboratory.
Ultra-high resolution real-time optical fiber strain sensor using a sideband interrogation method
Show abstract
We report a novel sideband interrogation method to measure the resonance frequency difference between optical
resonators. The laser carrier and a special designed sideband are simultaneously locked to the resonance frequencies of
two sensor heads, respectively. Based on this method, an ultra-high resolution optical fiber real-time strain sensor system
is built using a pair of identical fiber Fabry-Perot interferometers. A strain resolution of 0.05 nano-strain is demonstrated
experimentally, and the measuring frequency is 7 Hz.
Quasidistributed fiber sensor for precast concrete structures monitoring
Show abstract
The prestressing force is transferred to the concrete during the slack period of precast concrete structures fabrication. To
contribute to a better understanding of the armor compliant behaviors during the mentioned process, a custom quasidistributed
Bragg Grating optical fiber sensor system is designed, fabricated and embedded into a prestressed concrete
prismatic beam. The experimental works, the results, their discussion and finally the obtained conclusions are presented
in this paper.
Distributed transverse load sensing with tilted fiber Bragg gratings using optical frequency domain reflectometry
Show abstract
A simple and novel distributed tilted fiber Bragg gratings (TFBGs) based transverse load sensing system using optical
frequency domain reflectometry (OFDR) is proposed and demonstrated for the first time. The transverse load compresses
an elastomer material around the fiber and induces a broadband loss in the spectrum of the TFBG. The additional loss is
directly measured by the return loss spectrum of Fresnel reflection points introduced in the Rayleigh backscattering
trace. With the wavelength sweeping characteristic of OFDR, we realized distributed sensing by interrogating each of the
TFBGs with different wavelengths and observed a minimum crosstalk effect between sensors.
Temperature compensated microfiber Bragg gratings
Show abstract
In this paper, temperature compensated microfiber Bragg grating (mFBG) is realized by use of a liquid with a negative
thermo-optic coefficient. The effects of grating elongation and the index change of silica glass are compensated by the
liquid through evanescent-field interaction. As a result, the reflective wavelength shifts by only 30 pm when the
temperature varies from 15 to 60°C. The proposed method is promising due to the compactness and high flexibility of
the device.
Polarization dependency of surface plasmon resonance based tilted fiber Bragg gratings refractometers
Show abstract
The excitation of surface Plasmon resonances (SPRs) in nanometric-scale gold-coated tilted fiber Bragg gratings
(TFBGs) strongly depends on the input state of polarization (SOP) of the core guided light. It was recently shown that
rotating the linear state of polarization of the guided light by 90° with respect to the grating tilt allows not only to turn
the SPR on and off but also to automate the extraction of the refractometric data. In this paper, we thoroughly analyze
the dependency of the cladding mode resonances of gold-coated TFBGs with respect to the SOP. Our experimental
results bring additional information about the behavior of these plasmonic platforms.
Femtosecond laser inscribed phase masks for fibre Bragg grating sensor inscription
Show abstract
We present femtosecond laser inscribed phase masks for the inscription of Bragg gratings in optical fibres. The principal
advantage is the flexibility afforded by the femtosecond laser inscription, where sub-surface structures define the phase
mask period and mask properties. The masks are used to produce fibre Bragg gratings having different orders according
to the phase mask period. The work demonstrates the incredible flexibility of femtosecond lasers for the rapid
prototyping of complex and reproducible mask structures. We also consider three-beam interference effects, a
consequence of the zeroth-order component present in addition to higher-order diffraction components.
Post-processing techniques for enhancing mode-coupling in long period fiber gratings
Show abstract
Two promising post-processing techniques, i.e. applying tensile strain and rising temperature, are demonstrated to
enhance mode-coupling efficiency in the CO2-laser-carved long period fiber grating with periodic grooves. Such two
post-processing techniques can be used to enhance the resonant attenuation of the grating to achieve a LPFG-based filter
with an extremely large attenuation and to tailor the transmission spectrum of the grating to exactly equalize the gain of
erbium-doped fiber amplifiers.
Long period grating made by rocking a single mode fiber
Show abstract
Long period gratings (LPGs) can be made by rocking a single mode fiber and at the same time periodically scanning
a focused CO2 beam across the fiber. A 15 period LPG with ~ 3 degree rocking angle and 1.3 mm pitch exhibits a narrow
bandwidth of 4.8 nm and a resonant attenuation of 33.5 dB. The novel LPG has a temperature sensitivity of -77 pm/°C
and a strain sensitivity of -0.14 nm/mε , and is insensitive to twist.
An investigation of the crack propagation in a carbon fiber bonded joint using backface strain measurements with FBG sensors
Show abstract
Carbon-fiber structures has many advantages over traditional materials, but special care must be taken when bonded
joints are used. A crack can propagate and cause the failure of the structure. The presence of a crack and its length can be
monitored in example by means of backface strain measurements. In this work the backface technique is applied by
using an array of 10 Fiber Bragg Grating (FBG) sensors applied on a carbon-fiber bonded joint. This is an interesting
solution because these sensors can be embedded in carbon-fiber structures nearly without producing a load effect thanks
to their small cross section. Special care must be used with FBG sensors because the expected strain profile is
non-homogeneous (computed using a FEM analysis) and the FBG spectra can be altered and prevented from correct
measurements (simulations using a T-matrix model were conducted). The specimen was tested with a pulsating tensile
force, so that a crack developed and propagated below the optical sensors. The comparison of the observed crack
position and the one inferred from the measured position of the minimum of the longitudinal strain pattern showed a
good correlation, with errors lower than 10% except a small range where a 20% error was observed.
A novel design of a compact S-shaped balance with FBG sensors for the pantograph-catenary contact force measurement
Show abstract
The measurement of the contact force between pantograph and catenary in railway engineering has been carried out in
the past with conventional electrical load cells. This study evaluates the use of fiber Bragg gratings (FBG) sensors, so
that electrical insulation of the load cells, placed on high voltage parts, is obtained by means of the fiber optic intrinsic
insulation. While FGB sensors can be compared to traditional resistance strain gauges, their dimensional and strain
profile characteristics required the development of a novel load cell design. A trade-off between two opposite
requirements were made: an adequate sensitivity of the FBG output (high strains) and a high reliability (small strains).
Moreover the application requested predefined dimensional constrains. The selected design is basically an S-shaped load
cell. Static and dynamic calibrations were performed also to asses the separation of the effects due to axial force, bending
moment and temperature. Both test rig and in-service measurements has been performed, and the very first results show
the good operation. The main metrological characteristics are: design full scale of ±500 N with a static safety factor of 5,
equivalent spectral noise of 0.064 N/√Hz, first resonance frequency of mounted cell of about 200 Hz (so that a useful
range of at least (0 to 50) Hz is obtained).
On the time delays in swept laser FBG interrogators for control systems applications
Show abstract
FBG sensors are an attractive solution for vibration control applications since they can provide a large number of
measurements with a negligible effect on the mechanical properties of the controlled structure and without problems
related to measurement layout and overall dimensions. The paper analyzes the limits on the use of swept laser FBG
interrogators for control systems applications due to time delays. Results show that good control performance can be
obtained at least up to 20 Hz.
Experimental investigation of dynamic characteristics of wavelength of DFB-LD for FBG-FPI vibration sensor based on wavelength-to-time mapping
Show abstract
An in-fiber Fabry-Perot interferometer with fiber Bragg grating mirrors (FBG-FPI) yields extremely narrow transmission peaks within the FBG reflection wavelength range. Periodical scanning of the laser light source is under influence of strain. A high signal-to-noise ratio interrogation is possible with high resolution and a wide range of vibration frequency can be analyzed since the laser wavelength can be easily scanned at high frequency. Furthermore, an inexpensive DFB laser can be utilized as a light source because the narrowness of the transmission peaks does not require broad wavelength scanning. In this paper, experimental investigation of dynamic characteristics of wavelength of DFB-LD is reported.
Corrosion of Fe-C coated FBG sensor and rebars: a comparative study
Wenbin Hu,
Xiaoxing Chen,
Hanli Cai,
et al.
Show abstract
Corrosion of steel in structures has become a major cause of structural degradations. Corrosion detection and monitoring
are necessary for evaluation of structural service conditions. A novel FBG based sensor for steel corrosion detection and
monitoring is developed previously. In this paper the sensor performances are evaluated by comparing to the corrosive
rate of rebars in the corrosive environments. The correlation between the wavelength shifts of the sensor and the
corrosive depth is established. It is proved that the sensor responses successfully to the occurrence of rebar corrosion,
which shows the promising feasibility of applying the sensor for corrosion indicator.
Highly sensitive type IA fiber Bragg gratings as sensors in radiation environments
Show abstract
Type IA fiber gratings have unusual physical properties compared with other grating types. We compare with
performance characteristics of Type IA and Type I Bragg gratings exposed to the effects of Co60 gamma-irradiation. A
Bragg peak shift of 190 pm was observed for Type IA gratings written in Fibercore PS-1250/1500 photosensitive fiber at
a radiation dose of 116 kGy. This is the largest wavelength shift recorded to date under radiation exposure. The Type IA
and Type I gratings show different kinetics under radiation and during post-radiation annealing; this can be exploited for
the design of a grating based dosimetry system.
Refractometer based on a superimposed optical fiber grating
Show abstract
A refractometer based on a superimposed optical fiber grating, where a fiber Bragg grating (FBG) with broadband
reflection (~2.7nm) is superimposed in the rear part of a tilted fiber Bragg grating (TFBG), is proposed and
experimentally demonstrated. The superimposed grating is immersed in liquid with different refractive index. Optical
power reflected back by the FBG is modulated twice by the TFBG that greatly enhances the sensitivity. And by using the
broadband reflection FBG, instead of a normal FBG, signal to noise ratio is also improved.
Bragg gratings in few-mode Er/Al/Bi/P Co-doped germanosilicate ring-core fibre
Show abstract
We demonstrate the efficient inscription of Bragg gratings in a few-mode Bi and Er doped complex germanosilicate
ring-core fibre also containing P and Al. The thermo-optic properties and thermal stability of these gratings are presented
and the potential for sensing applications are discussed.
Acousto-optic modulation in a microstructured plastic optical fibre Bragg grating
Show abstract
The present work addresses the control of the mPOF Bragg grating spectrum properties through acousto-optic
modulation. For the first time, the interaction of a flexural acoustic wave, generated by longitudinal excitation of
different frequencies, with the Bragg grating will be presented. Also it will be demonstrated the quasi linear relationship
between PZT load and maximum reflected power/ 3dB bandwidth of the reflected spectrum.
Fiber optic anemometer based on distributed Bragg reflector fiber laser
Show abstract
A novel fiber-optic anemometer based on a distributed Bragg reflector (DBR) fiber laser is reported in this paper. We
design a fiber laser pressure sensing setup and a Venturi tube is designed for wind speed measurement. This fiber optic
anemometer overcomes the drawbacks of the existing wind sensors with its unique advantages, such as immunity to
electromagnetic interference, compact structure, remote detection, multiplexing capability. The measuring range of the
anemometer is 8m/s~40m/s, the sensitivity is about 0.3m/s, and the short term repeatability can up to 0.35%.
Experimental results reveal that the sensitivity is impacted by power of pump laser which could be further improved.
This anemometer has high sensitivity and possibility for multiplexing application on a single fiber.
Focal beam position detection in a laser induced breakdown spectroscopy system by using a fiber Bragg grating sensor
Show abstract
Chemical analysis of dangerous materials entails a safety issue for the researchers. Laser Induced
Breakdown Spectroscopy offers the possibility to analyze these materials away from them using Stand-Off Set-ups. To optimize the plasma induction, the remote focalization of the laser beam is of paramount
importance. A custom Fiber Bragg Grating sensor system able to correct the laser beam focalization
errors is proposed and experimentally checked. The optical transducer architecture and the preliminary
obtained results are reported in this paper.
Dynamic temperature compensation interrogation technique for liquid level sensors array based on single-longitudinal-mode DBR fiber laser
Show abstract
A polarimetric DBR fiber laser sensor array for simultaneous measurement of liquid level and temperature has been
proposed and experimentally demonstrated. Operation principle of the proposed DBR fiber laser sensor has been
theoretically analyzed. Based on beat frequency/wavelength hybrid interrogation, discrimination between liquid level
and temperature has been achieved. Furthermore, three fiber laser sensors were cascaded to build up a serially
multiplexed sensor array, showing a good multiplexing capability for potential network applications.
UV sensor based on azobenzene-polymer-coated FBG
Show abstract
Recently, an ultraviolet (UV) sensor based on a photomechanically responsible material and a fiber Bragg grating (FBG)
has been proposed by our group. The elasticity of the azobenzene polymer as a photo-responsive material is changed by
UV light, which induces a center wavelength shift corresponding to the variation in the azobenzene-coated FBG's period.
In this study, we test the performance and reliability of the abovementioned sensor.
Real-time activity identification in a smart FBG-based fiber-optic perimeter intrusion detection system
Show abstract
Activity identification is very important in a Perimeter Intrusion Detection System (PIDS). In this paper, an intelligent
FBG-based fiber-optic PIDS is presented, which can distinguish effects of different intrusion activities. The intrusion
identification method is proposed based on the Principal Component Analysis (PCA) to tell the essential dissimilarity of
the statistical characteristics of intrusion signal's modalities in the time domain. The experimental results show the
recognition rate can be as high as 96.52% for eight types of common intrusion events.
Long-distance fiber-optic point-sensing systems based on the second-order random fiber laser
Show abstract
The novel concept of utilizing the second-order random fiber laser (RFL) to realize long-distance fiber-optic pointsensing
systems is proposed. The sensing system consists of a pump laser, a fiber Bragg grating (FBG) at the pump side
and 100km single mode fiber (SMF), and another FBG at the end of the SMF. The first FBG is used to enhance the
lasing efficiency, and the second FBG is use as the remotely-located sensing head. The Bragg wavelengths of the two
FBGs correspond to the first-order and the second-order random lasing spectrum, respectively. Its ability for remote
temperature sensing is experimentally demonstrated.
Strain and temperature sensitivity of chiral long period fiber gratings
Show abstract
Mode couplings of the core modes to cladding modes with both lower and higher angular orders in chiral long period
gratings (CLPGs) are analyzed. The sensing sensitivity of the resonant wavelength in response to strain and temperature
are demonstrated, respectively. Both single- and double-helix CLPGs formed by silica and polymer fiber are considered.
This provides useful guidance for practical designs of CLPGs to enhance the optical sensing sensitivity of the strain and
temperature, or to decrease the environmental influence on spectral characteristics of CLPGs.
Thermal characteristics of silver-recoated regenerated grating sensors for high-temperature sensing
Yun Tu,
Shan-Tung Tu,
Yi-Hua Qi
Show abstract
We have successfully fabricated regenerated gratings (RGs) with silver coating in standard telecommunication fibers by
annealing and magnetron sputtering (MG) process. Optical testing showed that the optical properties of the silverrecoated
RGs were slightly affected by MG process. We performed thermal tests to evaluate the characteristics with
respect to a silver-recoated RG (SRCRG) sensor within the temperature of up to 600 °C. The experimental results
showed that the SRCRG sensor exhibited a satisfactory performance for its sensitivity, repeatability and stability. Results
from the experiments also revealed that the silver coating achieved good adhesion to fiber and could be used as a
conductive layer for the further electroplating process.
A 1.65 µm region external cavity laser diode using an InP gain chip and a fibre Bragg grating
Show abstract
We present the construction of an external cavity laser (ECL) diode using an InP semiconductor gain chip and a fibre Bragg grating (FBG), designed to have an emission wavelength that coincides with an absorption line of methane, to be used for spectroscopic gas sensing. The FBG was employed as a wavelength selective and feedback element, which will potentially provide the laser with wavelength tuning capability. Narrow linewidth lasing output of less than 5 MHz was achieved. To our knowledge, this is the first FBG based ECL in the 1.65 µm region.
Intensity-independent fiber coupled interrogation technique for fiber Bragg gratings by fiber Bragg gratings
Show abstract
A low cost, highly accurate and light intensity-independent sensor system for the analysis of fiber Bragg grating signals
based on fiber Bragg gratings in the detection unit is presented. The setup is based on two fiber Bragg gratings used in
reflection to analyse one sensing fiber Bragg grating. The Bragg gratings were inscribed in coated non-photosensitive
standard telecommunication fibers using an infrared femtosecond laser and the point-by-point writing technique. The
accuracy of this interrogation concept is presented by means of a temperature measurement with a resolution better than
0.12°C in a linear operation range of 20°C.
Designing sensing properties of the long-period fiber gratings coated with the LC layers
Show abstract
This work presents an investigation focused on the advanced tunable photonic components known as liquid crystal longperiod fiber gratings (LC-LPFGs). It is demonstrated that by coating the LPFGs with a thin low-birefringence 1800b LC layer the thermal sensitivity of the attenuation band can be significantly reduced. Moreover, for the LPFGs coated with a thin medium-birefringence 1702 LC layer, a fast and repeatable electrical switching of the attenuation band can be achieved.
Study and application of CFBG vibration sensor with symmetrical push-pull configuration
Show abstract
The author in the paper fabricates a novel type of chirped fiber Bragg grating (CFBG) vibration sensor with symmetrical
push-pull configuration. It is a typical mass-spring system mainly made up of CFBG, steel tube, mass block. A push-pull
configuration design makes it have not only high sensitivity but also function of temperature self-compensation. Using
CFBG instead of FBG as a sensing element makes its measuring range increase by a big margin. Adopting matching
demodulation technology solves availably the problem of demodulation speed. The sensor has excellent sensing
properties and been successfully applied to vibration monitoring and fault diagnosis on large rotating machinery.
A PGC demodulation based on differential-cross-multiplying (DCM) and arctangent (ATAN) algorithm with low harmonic distortion and high stability
Show abstract
A novel phase generated carrier (PGC) demodulation algorithm based on differential-cross-multiplying (DCM) and
arctangent function (ATAN) is proposed in this paper. We investigate the stability with light intensity disturbance (LID)
and the harmonic distortion due to nonlinearity both theoretically and experimentally. The nonlinearity of the proposed
PGC demodulation algorithm has been analyzed. Compared with the traditional PGC-arctan and PGC-DCM algorithm,
this PGC algorithm inherently has much lower total harmonic distortion (THD) as well as high stability with LID.
Poster Session 2: Biomedical and Chemical Sensor, Micro-structured Fiber Sensors, Sensor Multiplexing
Study of antibacterial effect of nanosilver particle by tapered optical fiber sensor
Show abstract
A single-mode nanoadiabatic tapered optical fiber biosensor was utilized for real-time monitoring of the antimicrobial
activity of silver nanoparticles (Ag-NPs) against E. coli. For measuring growth-inhibitory effects, the bacteria were
immobilized on the tapered surface. Then, fiber sensor surrounded in glucose growth medium conation different
concentration Ag-NP. At the same condition, the growth inhibition of E. coli was measured by colony counting method
as a controlling experiment. Interacting Ag-NPs with cells, by anchoring to and penetrating the bacterial cell, the
refractive index of the tapered region can be changed that leads to changes in the optical characteristics of the taper.
Label free detection of quadruplex formation of peroxidase-like DNAzyme by tapered fiber optic biosensor
Show abstract
We investigated the possibility the active DNAzyme formation of particular Guanine-rich oligonucleotide with
nonadiabatic tapered optical fiber (NATOF) sensor. These kinds of oligonucleotides can form stable four-stranded
structure called G-quadruplex in the presence of particular metal ions. Structural change of immobilized oligonucleotide
was detected by monitoring of transmission spectrum of the sensor. The formation of active DNAzyme formed was
confirmed by verifying enzyme activity. Result shows that the NATOF sensor has capability to detect intramolecular
structural changes and using this sequence as biorecognition molecule for fabricating fiber optic biosensor.
DNA detection using molecular beacon in soft-glass microstructured optical fibers
Show abstract
We report, for the first time to our knowledge, the detection of specific strands of DNA based on a soft-glass
microstructured optical fiber (MOF) platform loaded with molecular beacons (MBs). This detection scheme brings
together the intrinsic advantage of MOF for low-volume sensing with a label-free approach, and is highly specific in
identifying complementary (cDNA) from non-complementary (nDNA) sequences at room temperature. The detection
limit of the current sensing scheme is demonstrated to be improvable via coupling to different sets of guided core modes
by means of longitudinal offset in coupling light from the source to the fiber.
Optical coherence tomography for endoscopes, using imaging fibre bundles and a conical mirror
Show abstract
Imaging fibre bundles and a conical mirror have been used to construct a passive, endoscopic OCT probe with no
scanning components at the probe tip. Circular scanning of the beam projected onto the proximal face of the imaging
bundle results in a corresponding circular scan at the distal end of the probe. A 45° base-angle conical mirror turns the
output light to produce a radially-directed beam that permits circumferential OCT scanning in quasi-cylindrical ducts.
Instantaneous spectroscopic SS-OCT imaging using a simultaneous dual-band swept laser and common-path fiber probe
Show abstract
A simultaneous 1310/1550 swept-source optical coherence tomography system is implemented by combining a
novel dual-band swept laser source and an integrated common-path GRIN lensed fiber interferometer/probe. Highspeed
synchronized dual-wavelength tuning is performed by using two laser cavities with a single dual-window
polygonal. Simultaneous in vivo OCT imaging at 1310 and 1550 nm is demonstrated. This dual-band technique
bring together common-path fiber probe potentially allows instantaneous in situ functional OCT imaging with high
quality spectroscopic contrast and stable phase measurements.
Temperature compensation fiber-optic refractive index sensor based on single-mode fiber core-offset attenuator
Show abstract
This paper has developed a novel single-mode core-offset fiber optic sensor based on the principle of Michelson
interferometer, which can be used for refractive index measurement in sugar solution while making temperature
compensation to eliminate or weaken temperature sensitivity. Experimental results show that when the temperature range
is from 18.1°C to 84.3°C there will be an increasing relationship between characteristic wavelength and temperature.
When the sensor's sensing range is from 1.331 to 1.335, there will be a better decrease gradually relationship between
characteristic wavelength and refractive index (0.0416nm/0.01R.I.U) after temperature compensation. This sensor has a
simple-structure and high-sensitivity.
Label-free DNA biosensor based on cladding-etched thin-core fiber modal interferometer
Show abstract
The fabrication and characterization of a highly sensitive DNA biosensor based on thin-core fiber modal interferometer
(TCFMI) are presented. The TCFMI is made by using a thin-core fiber (TCF) with core diameter of ~3.0 μm and etched
by using Hydrofluoric (HF) acid solution for sensitivity enhancement. A thin layer of polymer (PLL, poly-L-lysine) was
coated on the sensor surface and experimentally demonstrated for the detection of hybridization of deoxyribonucleic acid
(DNA).
A novel biosensor based on a coupled surface plasmon nanostructure
Show abstract
A novel plasmonic biosensor based on coupled metal-dielectric buffer grating is proposed and analyzed by the rigorous
coupled wave analysis (RCWA) method. The metal-dielectric buffer grating structure offers surface plasmon resonance
suitable for high sensitivity biosensing applications. The calculated FWHW (full width at half maximum) of the
transmission peak is 5 nm and the optical transmission efficiency is significantly enhanced at the resonant wavelength of
800.8 nm by introducing the dielectric buffer grating. The highly concentrated field distribution is sensitive to
surrounding refractive index changes of the metal surface providing a sensitivity of 560 nm/RIU (refractive index unit)
for optical biosensing applications.
Dual-band wavelength-swept active mode locking laser for multi-band fiber-optic sensors
Show abstract
This paper shows experimentally dual wavelength swept at multi band (O,C-Band) property with active mode
locking (AML) method. Unlike conventional wavelength swept laser, AML wavelength swept laser does not require any
wavelength selecting filter in the cavity. The cavity has two free spectral ranges (FSRs) depend on dual path
configuration. This wavelength swept laser can be useful for wide-band fiber-optic application such as Optical
Coherence Tomography and Fiber Bragg Grating sensor system.
Dispersion-tuned wavelength-swept fiber laser using a chirped FBG and a reflective SOA for OCT applications
Show abstract
We demonstrate a wavelength-swept fiber laser based on the dispersion tuning method using a chirped fiber Bragg
grating (CFBG) and a reflective semiconductor optical amplifier (RSOA). The laser cavity length is reduced to as short
as 2m owing to the short and highly-dispersive CFBG, which is much shorter than the one using dispersion
compensating fiber (DCF). The short cavity enables higher sweep speed. We successfully obtain the OCT images of a
rolled adhesive tape at the sweep rate of 50kHz.
Fabrication and characterization of fiber-optic dosimeters for diagnostic radiology usages
Show abstract
A water-equivalent fiber-optic dosimeter was fabricated using an organic scintillator, a plastic optical fiber and a photo-multiplier
tube for real-time dosimetry in diagnostic radiology. We measured the scintillating lights, which are changed
due to the exposure parameters, by using the fiber-optic dosimeter placed on top of the acrylic-aluminum chest phantom
to provid a backscatter medium. The light output signals of the fiber-optic dosimeter were compared with entrace surface
doses obtained using a dose-area product meter and a semiconductor dosimeter.
A label-free antigen-antibody immunosensor based on a special double cladding fiber
Show abstract
An optical fiber label-free antigen-antibody immunosensor was proposed and demonstrated. It was fabricated by a
special double cladding fiber (DCF) which presents a band-rejection resonant transmission spectrum. With the 3-
aminopropyltriethoxysilane (KH-550) as the crosslink agent, goat anti rabbit IgG was immobilized on the surface of the
DCF sensor. The whole process of immobilization and the antigen-antibody reaction was monitored through the shifts of
the cladding mode resonant spectrum. Experimental results show that the resonant spectrum shifted toward longer
wavelength during antigen-antibody reaction process. And the spectrum shift presented a saturation trend at high
concentration rabbit IgG.
Strain monitoring of the periodontal ligament in pig's mandibles
Show abstract
The objective of this study is to propose a new method to monitor the response of the periodontal ligament (PDL) to
loading to understand its mechanical and physical properties. Fiber optic sensors are used to monitor internal strain (με)
in the PDL in a pig mandible simulating longitudinal forces applied on the tooth. This consists therefore of an in vitro
study. Results show that the sensor is sensitive to investigate external loading and unloading in the PDL. The results can
help the study of PDL properties.
Sensing biodiesel and biodiesel-petrodiesel blends
Show abstract
This work describes two approaches for refractometric sensors based on cascaded long period gratings for evaluating
substances with refractive indices equal to or higher than the fiber cladding at room temperature. The devices are
experimented on the assessment of fuel quality regarding the presence of remaining vegetable oil in biodiesel, as well as
to determine the concentration of biodiesel in the biodiesel-petrodiesel blends.
Structure optimization of slotted photonic crystal waveguide for gas sensor
Yong Zhao,
Ya-Nan Zhang,
Di Wu,
et al.
Show abstract
To realize a high sensitivity gas sensor, a large wideband, temperature stabilized and large light confinement slow light
structure in slotted photonic crystal waveguide (SPCW) is designed. The simulation results indicate that with a proper
optimization of the SPCW structure, a very high group index of 105 can be achieved and the electric field enhancement
factor would reach to 12. Combined with the correlation spectroscopy for signal processing, the detection limit of 10
ppm is achieved.
Effect of the clad transparency condition in POF humidity sensors with the swelling polymer clad
Show abstract
We have developed plastic optical fiber (POF)-type humidity sensors, which consist of swelling polymer cladding.
The proposed sensor consists of a polyvinylpyrrolidone (PVP) cladding layer that surrounds a poly(methyl methacrylate)
core. The operation of the sensor is based on the POF structure changing from a leaky-POF to a guided-POFbecause of
the changes in the refractive index caused by swelling of the cladding layer in high humidity. Therefore, the clad
transparency condition before swelling affects the sensitivity of the sensor.
In this study, to investigate the effect of the clad transparency condition, we fabricated three types of POF humidity
sensors, which have different transparent cladding. The results indicate that the sensitivity of the sensor was improved by
using the dye-doped swelling polymer clad.
Study of ring-down signal processing for fiber-loop ring-down sensing technology
Show abstract
This paper develops a program to process the ring-down signal automatically finding peaks and calculating decay rate.
The program is tested by simulated data and analyzes the error under different SNR. Experimental system is set up to
acquire ring-down signal that is processed by data processing program.
An optical fibre salinity sensor based on fluorescence quenching mechanism
Show abstract
Salinity measurement is very important for many industrial applications and in this work an intrinsic optical fibre-based
salinity sensor is developed specifically for the detection of the salt water concentrations. The sensing principle was
based on the fluorescence quenching as a result of the interaction between the sensing material incorporated into the tip
of an optical fibre and target chloride ions in salt solutions. The peak intensity of the fluorescent signal generated has
shown to change with the change of the salinity of the solutions measured. The experimental data obtained are in good
agreement with a modified theoretical model when the hydrophobicity of the silicone supporting material is taken into
account, thus demonstrating a clear feasibility of the developed sensor system of this type.
Comparison of side-polished fiber Bragg grating hydrogen sensors sputtered with Pd/Ag and Pd/Y composite films
Show abstract
Pd/Ag and Pd/Y composite films were deposited on the side-face of side-polished fiber Bragg grating (FBG) as sensing
elements with magnetron sputtering process. Compared to standard FBG coated with same hydrogen sensitive film,
side-polished FBG significantly increase the sensor's sensitivity. When hydrogen concentration is 4% in volume
percentage, the wavelength shifts of side-polished FBG sputtered with Pd/Ag and Pd/Y are 18 and 23 pm respectively.
The experimental results show the hydrogen sensor coated with Pd/Y composite film has higher sensitivity and quicker
response rate, and the sensor's hydrogen response is reversible. The side-polished FBG hydrogen sensor with Pd-based
composite films has great potential in measurement and monitor of hydrogen concentration.
Long period grating inscribed by femtosecond laser for refractive index measurements in aqueous environments
Show abstract
A sensor based on a Long Period Grating (LPG) for measurement of the refractive index (RI) of liquids with RI close to
that of water is reported. An LPG was written by a femtosecond laser (F-LPG) operating at 800nm, utilizing a point-bypoint
technique. The performance of the F-LPG is compared with an LPG written by ultraviolet irradiation (UV-LPG).
For low RIs, the sensitivities of the F-LPG and UV-LPG are 130 nm/RIU and 3.1 nm/RIU, respectively. For higher RI,
the F-LPG exhibited sensitivity as high as 249 nm/RIU. For the low range of RI, the resolution of F-LPG was 3.8 x 10-5.
Real-time monitoring of fermentation process applied to sugarcane bioethanol production
Show abstract
The application of a Fresnel-based fiber sensor on real-time monitoring of the fermentation process in bioethanol
production is reported. The fiber was placed inside the bioreactor, and experiments were conducted by using glucose
solution and sugarcane syrup as substrates for fermentation. When the sugar is completely consumed, there is no
production of ethanol, causing the sample concentration to become constant, as well as the reflected light intensity.
Therefore, the sensor can be used to predict the ideal moment to terminate the process. The results were confirmed by
additional laboratory analysis, making this an alternative technology for optimization of bioethanol production.
A fiber-optic methane gas sensor system with improved accuracy using absorption-spectrum matched comb filter
Show abstract
A fiber-optic methane gas sensor system is proposed and demonstrated with accurate gas concentration measurement
with a sensitivity of ~410ppm. We employ the polarization-maintaining photonic crystal fiber (PM-PCF) based Sagnac
loop filter to slice the spectrum of broadband light source so as to precisely match multiple absorption lines of the
methane gas. Meanwhile, a compact gas cell with multiple reflections is designed to enhance the interaction between
methane gas and the light beam. The proposed gas sensor is verified as low cost, temperature-insensitive, and high
sensitivity.
Enhanced RI sensor using a combination of a long period fiber grating and a small core singlemode fiber (SCSMF) structure
Show abstract
An enhanced refractive index (RI) sensor with combination of long period fiber grating (LPG) and a small core
singlemode fiber (SCSMF) structure is proposed and developed. Since the LPG and SCSMF transmission spectra
experience a blue and red shift respectively as the surrounding RI (SRI) increases, the sensitivity is improved by
measuring the separation between the resonant wavelengths of the LPG and SCSMF structures. Experimental results
show that the sensor has a sensitivity of 1028 nm/SRI unit in the SRI range from 1.422 to 1.429, which is higher than
individual sensitivities of either structure alone used in the experiment.
Numerical modeling and performance optimization of QEPAS spectrophone
Show abstract
The spectrophone performance for QEPAS is numerically investigated by using a finite element method. The effect of
varying system parameters such as the excitation frequency, relative position between the acoustic resonant tubes and the
quartz tuning fork, and the dimensions of resonant tubes are examined A pair of rigid tubes, each with a length of 5.1
mm and an inner diameter of 0.2 mm, positioned 0.6 μm down from the opening and 20 μm away from the edge of
tuning fork is suggested for optimal spectrophone performance.
Coating based fiber Bragg grating humidity sensor array
Show abstract
A coating based FBG humidity sensor is developed for distributed humidity sensing. The sensitivity of the coated FBG is
optimized by varying the chemical composition and the thickness of the coating. A sensitivity of ~2 pm/%RH and a
rapid response are demonstrated. The composition of the coating can be adapted for sensing other chemical elements.
For the design and modeling of the responsive polymer coatings, a toolbox is developed. Using this toolbox, sensors for
sour gas like CO2 and H2S for the Oil&Gas industry are developed. The results match well with the prediction.
Using optical fiber sidewall to capture light from an adjustable depth
Show abstract
It is commonly accepted that light captured by the fiber core sidewall is from a depth of less than 1 μm limited by the
evanescent-wave (EW) field. Yet we demonstrate in this paper that, with some simple modifications, the fiber core
sidewall is also able to capture light from an adjustable depth beyond the EW field. The key elements are an air-clad
fiber core cylinder; a liquid sample droplet surrounding a short segment of the core; a narrow, collimated and position-tunable
excitation beam perpendicular to the fiber axis to excite the sample. A theoretical investigation of the operation
of the mechanism is given, which is verified by a preliminary experiment.
Fiber optic pH sensor with self-assembled multilayer nanocoatings on tilted FBG
Show abstract
A novel fiber optic pH sensor is experimentally demonstrated by coating multilayers of poly(acrylic acid) (PAA) and
poly(diallyldimethylammonium chloride) (PDDA) on a tilted fiber Bragg grating (TFBG) with the layer-by-layer (LbL)
electrostatic self-assembly method. The utilization of PDDA/PAA pH sensitive polymeric coating presents a variation of
the thickness with the pH of the solution, which introduces the wavelength shift and transmission change in the spectrum
of TFBG. Using fast Fourier transform (FFT) analysis on a selected bandwidth of the transmission spectrum, it is found
that the peak amplitude of the dominant spectral fringes increases with the increasing pH value with an near-linear
sensitivity of 117 arbitrary unit (a.u.)/pH unit (in the range of pH 4.66 to pH 6.02). The dynamic response of the sensor
also has been studied (10 s rise time and 18 s fall time)
SnO2 based optical fiber refractometers
Show abstract
In this work, the fabrication and characterization of refractometers based on lossy mode resonances (LMR) is presented.
Tin dioxide (SnO2) films deposited on optical fibers are used as the LMR supporting coatings. These resonances shift to
the red as a function of the external refractive index, enabling the fabrication of robust and highly reproducible
wavelength-based optical fiber refractometers. The obtained SnO2-based refractometer shows an average sensitivity of
7198 nm/refractive index unit (RIU) in the range 1.333-1.420 RIU.
Miniature photonic crystal optical fiber humidity sensor based on polyvinyl alcohol
Show abstract
A compact photonic crystal fiber (PCF) humidity sensor based on modal interference has been proposed by the use of
commercial fusion splicer to collapse the holes of PCF to form a Michelson interferometer with cladding mode
excitation at the fiber tip. The sensor is then dipped coated in polyvinyl alcohol to make it sensitive to humidity. The
shift of the interference fringes was measured when the sensor was placed in a humidity chamber of varying humidity.
High sensitivity was obtained when the relative humidity is above 50% RH as an exponential relation of relative
humidity and interference shift was established.
High finesse interferometric hydrogen sensor based on fiber-optic Fabry-Perot cavity modulations
Show abstract
Fiber-optic hydrogen sensing technique based on an extrinsic Fabry-Perot interferometer (FPI) composed of a palladium
(Pd)-coated high finesse cavity is proposed and experimentally demonstrated. As the Pd layer absorbs hydrogen gas, the
FPI cavity length is reduced so that we can measure the wavelength shift of its interference spectrum. The sensing
performance of the proposed sensor is presented in terms of spectral response to hydrogen and recovery by nitrogen.
An evaluation of the distribution of metal ions in otherwise uniform titania sol-gel layers designed for optical sensing using laser ablation inductive coupled plasma mass spectroscopy
Show abstract
Free-base porphyrins are bound to titania sol-gel layers deposited on glass slides. The porphyrin-containing titania layers
show the UV-VIS spectra of the porphyrin and are found to be uniformly and evenly distributed. By addition of a metal
salt to the titania layer, it was possible to metallate the free-base porphyrin within and change the UV-VIS absorbance of
the porphyrin. The metalloporphyrins based on Cu and Zn ions could be detected by laser ablation inductive coupled
plasma mass spectroscopy (LA-ICP-MS). Aggregation of metals is observed indicating that metal ions are also attaching
directly to the titania. In samples where already metalized porphyrins are used little or no aggregation is observed,
indicating that the titania sol gel is non-uniform in its affinity for metal ions.
Highly-sensitive temperature-independent refractive index sensor based on compact highly-birefringent microfiber loop
Show abstract
A compact microfiber sensor is implemented with the twist of a continuous rectangular microfiber. The structure can exhibit extremely-high sensitivity of around 24,373nm per refractive-index unit and temperature stability of better than 0.005nm/oC, implying a great suppression of cross-sensitivity. Thia sensor is featured with compact size, high sensitivity, easy fabrication, robustness, and low connection loss with all-fiber system.
Suppression of long distance instability on remote sensing signal of pulse correlation measurement in optical fiber sensing
H. Kobayashi,
T. Tsuzuki,
T. Onishi,
et al.
Show abstract
Optical fiber sensing has potential to overcome weak points of the traditional electric sensors. Many types of optical
fiber sensors have been proposed according to the modulation parameter of incident light. We proposed optical pulse
correlation sensing system which focuses the time drift values of the propagating optical pulses to monitor the
temperature- or strain-induced extension along the optical fiber transmission line. In this study, we stabilize the pulse
correlation signal instability due to the time drift fluctuation at the long transmission line to purify the response and
improve the accuracy of signals at the focused sensing regions.
Tunable diode laser spectroscopy with electronically controlled background RAM nulling
Show abstract
An electronically-controlled fibre-optic RAM nulling method is presented for tunable diode laser spectroscopy (TDLS)
of gases. An electronic variable optical attenuator and a 1x2 optical switch are used to demonstrate the cancellation of
the background RAM signal that limits the detection sensitivity in 1f WMS. This is an significant improvement upon the
generic RAM nulling method that has recently been shown to be well suited to direct recovery of the absolute gas
absorption line shapes of gases that commonly encountered in process control applications.
Increased sensitivity of long period grating hydrogen sensors through coupling to higher order cladding modes
Show abstract
We investigate the phase matching conditions and sensitivities of higher order metal jacketed long period gratings
(LPGs). These higher order modes have been previously demonstrated to have flatter, and therefore more sensitive,
phase matching conditions leading up to the phase matching turning point. We demonstrate this increased sensitivity as
applied to a Pd jacketed LPG hydrogen sensor illustrating an improvement in both the refractive index and temperature
sensitivity (of the 17th order mode) of an order of magnitude over the lower order (1st-9th) modes.
Chemical vapor sensing properties of twin-core photonic crystal fiber based in-reflection interferometer
Show abstract
This paper presents chemical vapor sensing properties of twin-core photonic crystal fiber-based in-reflection
interferometer. The interferometer is composed of end-cleaved twin-core photonic crystal fiber (TC-PCF) and fiber
circulator. Infiltrating chemical molecules in the air holes of TC-PCF lead to change in inter-core effective index
difference and associated fringe shift in the interferometer. As an example we demonstrate acetone vapor detection and
discuss the potential applications of the proposed device.
Fiber carbon monoxide sensing system and its application in coal mines
Show abstract
Spontaneous combustion in coal goaf area is one of major disasters in coal mines. Detection technology based on
signature Gas is the primary means of spontaneous combustion forecasting of coal goaf area. A real-time remote fire gas
detection system is proposed based on tunable diode laser absorption spectroscopy technology, to achieve valid test of
Carbon Monoxide signature gas. The System uses the wavelength, respectively 1.567um near-infrared band fibercoupled
distributed feedback laser (DFB) as the light source, combined wavelength modulation spectroscopy and
harmonic detection technique, developed a fiber-coupled white-type long-path gas absorption cell, to achieve high
sensitivity detection of gas concentration. The system achieved a remote on-line monitoring of Carbon Monoxide gas
concentration, to meet the fire forecast need for Coal Mine goaf area.
LPG based fiber optic sensor for carbon dioxide
Show abstract
In this work a novel optical-fiber sensor for carbon dioxide measurement is presented. A polymeric sensitive layer based
on the acid-base equilibrium of phenol and of its derivative 4-nitro-phenol is used for carbon dioxide determination. The
sensitive material presents changes in color and in its refractive index. Colorimetric and refractometric measurements
were performed. The results show the sensor is more sensitive for lower concentrations and a saturation effect occurs for
higher levels. For the colorimetric response, a resolution of ±0.15% was estimated and a response time of 30s was
measured. For the refractometric measurements, a resolution of ±0.50% could be estimated and a response time of 12s
was measured. Reversibility and reproducibility were also demonstrated.
Simultaneous measurement of refractive index and temperature based on multimode interference inside a fiber loop mirror
Show abstract
A fiber optic sensor for simultaneous measurement of refractive index and temperature is presented. The sensing probe is
achieved by introducing multimode interference inside a high birefringence fiber loop mirror resulting in a configuration
capable of refractive index and temperature discrimination. The multimode interference peak is sensitive to the
surrounding refractive index (90 nm/RIU) and slightly responsive to the temperature (0.005 nm/°C). On the other hand,
the birrefringent fiber loop mirror is highly sensitive to temperature (2.39 nm/°C) and has no response to refractive index.
Therefore, a temperature independent refractive index measurement can be made with a resolution of ±2.5x10-5.
SERS properties of gold core silver shell nanoparticles self-assembled on silica substrates and optical fiber endface
Show abstract
Gold core silver shell nanoparticles with different molar ratios of gold and silver were prepared by chemical reduction
with microwave heating method. Uv-vis absorption spectrometer and transmission electron microscope (TEM) were
used to detect their absorption and surface topography. The results show that core-shell nanoparticles had controllable
size and uniform distribution. With Rhodamine 6G (R6G) as detection molecules, gold core silver shell sol with a molar
ratio of 1:10 had the best surface-enhanced Raman scattering (SERS) effect. And we detected 10-17 mol/l and 10-9mol/l
R6G solution respectively after they were self-assembled on silica substrates and optical fiber endface.
Temperature independent refractive index measurement using white light interferometry
Show abstract
In this work a fiber optic interferometric system for differential refractive index measurement is described. The system is
based on a white light Mach-Zehnder configuration, with serrodyne phase modulation, to interrogate two similar nonadiabatic
tapered optical fiber sensors in a differential scheme. In this situation it is possible
to measure the refractive index independent of temperature. Signal processing with low cost digital instrumentation
developed in Labview environment allows a detectable change in refractive index of Δn≈2x10-6, which is, from the best
of our knowledge the highest resolution achieved using a fiber taper device. The results demonstrate the potential of the
proposed scheme to operate as chemical and biological sensing platform.
Enhanced novel fiber-optic sensor for efficient fluorescence collection
Show abstract
In this article the enhancement of the novel fiber-optic fluorescent sensor is demonstrated. The novel sensor that was
developed by our group is based on the collection of the fluorescence from the sidewall of the multimode optical fiber
which is partly de-cladded and covered by the sample under the test (SUT). The most part of the fluorescent intensity is
carried by the leaky rays which are inaccessible in traditional evanescent-wave fluorescence fiber sensors. In our
previous structure, some part of a refracting power is collected in the de-cladded segment and used to excite the lower
order lossless modes in the cladded part by an end-face mode-mixer. In the enhanced type of our sensor we discovered
that the mode-mixer on the side-wall, rather than on the end-face, is more efficient. The fluorescence efficiency
increased in this type of enhanced sensor by about 88%. Moreover, the capability of multiplexing of the different SUT
on one fiber is a promising advantage of this architecture with a view to develop the multi-channel chemical detection
system with inexpensive simple fiber-optic.
Temperature independent microbending polarization maintaining photonic-crystal-fiber based microdisplacement sensor
Show abstract
A temperature independent microdisplacement sensor based on microbending-induced core-cladding mode coupling loss
via a polarization maintaining photonic-crystal-fiber (PMPCF) is presented. By core-offsetting one splice joint between
the single mode fiber (SMF) and PMPCF in an SMF-PMPCF-SMF structure, one core-cladding modal interferometer
can be constructed. By packaging the interferometer in a carbon-fiber-composite based simple-supported beam,
temperature independent microdisplacement measurement can be achieved by monitoring the extinction ratio variation
of the interference spectrum. This type of sensor exhibits the advantages of temperature independent, high sensitivity and
simple structure.
Liquid-core photonic crystal fiber based surface plasmon resonance refractive index sensor
Show abstract
A surface plasmon resonance refractive index sensor based on a liquid-core photonic crystal fiber is proposed and numerically investigated through the finite element method. The effects of the central metallic analyte channel diameter, the cladding air hole diameter and the liquid-core diameter on the resonant spectrum are studied. A single-resonance and highly sensitive feature of the fundamental mode are utilized to perform the sensing, and a resolution of 2.7×10-6 RIU is achieved. The results show that the sensor is rather sensitive to the structural parameters and the resonant wavelength can be tuned to a desired value.
Temperature threshold sensor based on optical switch with filled photonic crystal fiber
Show abstract
In this paper we present the technology and experimental results of the intensity based fiber optic threshold temperature
sensor. As an optode of the sensor it was used a patch cord with an organic mixture filled photonic crystal fiber. Under
temperature changes the used mixture changes its state from solid to liquid one and this effect decides about intensity of
a transmitted light. A fabricated patch cord with VCSEL as a light source can be easy to use, flexible, cheap and low
power consuming sensor. The used technology gives a possibility to design optodes with different transition
temperatures in order to make sensor arrays.
Hollow-core photonic bandgap fiber Mach-Zehnder interferometer based on a long period grating and an offset-splice joint
Show abstract
We report a compact in-fiber Mach-Zehnder interferometer (MZI) made along a hollow-core photonic bandgap fiber
(HC-PBF). The MZI uses a long period grating (LPG) and an offset-splice joint (OSJ) which act as beam splitter and
combiner respectively. The LPG was produced by use of a high frequency pulsed CO2 laser, and the OSJ was made in
serial with the LPG by using a commercial fusion splicer. The interference is between the fundamental core mode (FCM)
and a high-order core mode (HOCM). The proposed interferometer was experimentally tested for temperature and strain
measurements, and the sensitivities of the interference fringe dip wavelength to temperature and strain are 107.5 pm/
(°C-m) and -1.24 pm/με, respectively.
An inline ultrasensitive temperature sensor based on liquid-filled photonic crystal fiber Mach-Zehnder modal interferometer
Show abstract
We propose an ultrasensitive temperature sensor based on an in-line liquid-filled photonic crystal fiber (PCF) Mach-
Zehnder interferometer. It consists of a small piece of index-guiding PCF fully infiltrated by fluid and two standard
single-mode fibers offset spliced with the PCF. Two core modes of LP01 mode and LP11 mode are conveniently utilized
as optical arms to form an in-line Mach-Zehnder-type interferometer. Experimental and theoretical investigation of its
response to temperature confirms that and a high temperature sensitivity up to -0.244nm/(oC-mm) could be realized by
such a compact inline liquid-filled PCF Mach-Zehnder interferometer.
Sensitivity enhancement in photonic crystal fiber interferometer
Sun-jie Qiu,
Ye Chen
Show abstract
In this paper, we demonstrated two methods to enhance refractive index (RI) and
temperature sensitivity of a photonic crystal fiber (PCF) in-line modal interferometer built via
fusion splicing, respectively. First we fabricated a tapered PCF interferometer by an etching
method with acid microdroplets. The RI sensitivity greatly increases (5 times) and the size
decreases after tapering the PCF, while the temperature sensitivity does not change a lot.
Then we obtained another PCF interferometer by inserting a short isopropanol-filled PCF
between two single mode fibers (SMFs). The temperature sensitivity increases over an order
of magnitude compared with the previous non-polarimetric sensors based on air-filled PCF
interferometers.
Simultaneous measurement of strain and temperature based on clover microstructured fiber loop mirror
Show abstract
In this work, an all-fiber loop mirror using a clover microstructured fiber for the simultaneous measurement of
temperature and strain is presented. The sensing head is formed by a short piece of clover microstructured fiber with 35
mm length. The geometry of the fiber allowed observing different interferences created by the microstructured fiber core
section. Different sensitivities to temperature and strain were obtained and, using a matrix method, it is possible to
discriminate both physical parameters. Resolutions of ±2ºC and ±11 με, for temperature and strain, respectively, were
attained.
Hollow core photonic crystal fiber as a viscosity sensor
Show abstract
Determining viscosity of nano-liter liquids is challenging, since most viscometers tend to use large volumes. We use
short lengths of hollow-core photonic crystal fibres to determine the viscosity of small volumes of two types of monosaccharides
diluted in a phosphate buffer solution. The simple optical technique used is based on the change in
propagation characteristics of a laser beam travelling through the fibre as it fills with the nano-litre liquid of interest via
capiliary action. The fiber length was kept in a temperature controlled casing, to minimize temperature differences across
the fiber length for reproducibility and minimal error.
Chromatic dispersion measurement in photonic crystal fiber by white-light interferometry
Show abstract
A dispersion coefficient measurement of photonic crystal fiber by using white-light interferometry based technology is
presented. A section of photonic crystal fiber (PCF) is fused in one arm of a Mach-Zehnder interferometer, and the
relative phase, delay time and chromatic dispersion coefficient of PCF are calculated by sweeping the wavelength from
1525nm to 1565nm. A section of PCF with the length of 0.779m is measured and the experimental results are shown.
The result indicates that the proposed method can measure the chromatic dispersion of PCFs with a reliable accuracy.
Pressure-assisted low-loss fusion splicing between photonic crystal fibers and single-mode fiber
Show abstract
We demonstrated a novel method of low-loss splicing photonic crystal fiber (PCF) and single-mode fiber (SMF) by
conventional electric arc fusion splicer, in which the air with proper pressure is injecting into the PCFs holes to control
the collapse ratio and then an optimum mode field match at the joint of SMF/PCF is realized. The experimental results
show that the splice loss at 1550nm is ~0.40 dB and ~1.05dB for solid-core PCF/SMF and hollow-core PCF/SMF,
respectively. This method could be widely used to fabricate PCF Devices.
Hydrostatic pressure sensor using two-core photonic crystal fiber
Show abstract
A hydrostatic pressure sensor based on a custom made two-core photonic crystal fiber (TC-PCF) is experimentally
demonstrated. The TC-PCF was fabricated in our lab using standard PCF fabrication techniques. A hydrostatic pressure
sensor based on the in-line fiber Mach-Zehnder interference is reported. The two solid cores of the TC-PCF separated by
an air hole acted as the two arms in the interferometer. The pressure sensor has high repeatability and high sensitivity of
-54.06 pm/MPa.
Photonic crystal fiber-based silver-nanowires LSPR sensors with supermodes
Show abstract
A photonic crystal fiber-based localized surface Plasmon resonance sensor with supermodes is analyzed. In the
boundary condition of anisotropic perfectly matched layer (PML), a full-vector finite element method (FEM)is used to
calculate the fiber model. Numerical results indicate that the excitation of the plasmon mode is sensitive to the change of
the refractive index of adjacent analyte. The maximum amplitude sensitivity of the fiber sensor is 1124dB/RIU. Its
resolution can reach 4×10-5 RIU. The maximum spectral sensitivity of the sensor can be about 2000nm/RIU. Its
resolution can reach 5×10-6 RIU.
Hybrid square-lattice photonic crystal fiber with high birefringence and negative dispersion
Show abstract
We have proposed a hybrid square-lattice PCF using two different sized air holes and conventional square lattice
cladding structure. Based on the plane wave expansion method and finite element method, we numerically investigated it
polarization and dispersion properties compared to the conventional square lattice photonic crystal fiber. From the
numerical results, it is shown that the proposed structure provides high birefringence and still maintains negative
dispersion property. Numerical results show that the birefringence of the hybrid square-lattice PCF reaches 10-2. The
value and slope of the chromatic dispersion are also negative over the C band.
Optical fiber sensors fabricated by the focused ion beam technique
Show abstract
Focused ion beam (FIB) is a highly versatile technique which helps to enable next generation of lab-on-fiber sensor
technologies. In this paper, we demonstrate the application of FIB to precisely mill the fiber taper and end facet of both
conventional single mode fiber (SMF) and photonic crystal fiber (PCF). Using this technique we fabricate a highly
compact fiber-optic Fabry-Pérot (FP) refractive index sensor near the tip of a fiber taper, and a highly sensitive in-line
temperature sensor in a PCF. We also demonstrate the potential of using FIB to selectively fill functional fluid into
desired patterns of air holes in a PCF.
Surface plasmon resonance sensor based on a novel grapefruit photonic crystal fiber
Show abstract
We propose a novel surface plasmon resonance sensor design based on a grapefruit photonic crystal fiber. In such a
sensor, phase matching between plasmon and a core mode is achieved by introducing microstructure into the fiber core.
Using the finite element method, the confinement loss of the fiber is calculated to measure the sensitivity of the sensor.
Simulation results show that this kind of sensor has an excellent effect, with the amplitude resolution to be as low as
2.88×10−5 RIU and the spectral resolution to be 6.67 ×10−5 RIU.
Microstructured polymer optical fiber-based surface plasmon resonance sensor
Ying Lu,
Baoqun Wu,
Xiangyong Fu,
et al.
Show abstract
We propose a surface plasmon resonance sensor based on microstructured polymer optical fiber (mPOF) made of
polymethyl methacrylate (PMMA) with the cladding having only one layer of air holes near the edge of the fiber. In such
sensor, the nanoscale silver metal film can be deposited on the outer side of the fiber, which is easily realized.
Numerical simulation results show that spectral and intensity sensitivity are in the range of 8.3×10-5~9.4×10-5RIU.
Overcoupled bending insensitive holey optical fiber coupler
Show abstract
A holey optical fiber (HOF) wavelength division multiplexing (WDM) coupler, which divides optical waves according
to their wavelengths, has been made by using the Fused Biconical Tapered (FBT) method. The transmission band of the
proposing HOF WDM coupler could be easily tuned by adjusting the pulling length during the FBT process. The HOF
used for the WDM coupler was designed to be bending insensitive, which could withstand a bending radius of up to 6
mm. Interestingly, it was observed that the air hole structure of the HOF should be maintained to have the property of a
WDM coupler. The cross sectional SEM images of the implemented HOF WDM coupler are presented along with the
light intensity distribution at the coupling region. The proposed HOF couplers may find applications as optical CWDM
(coarse wavelength division multiplexing) filters and as optical fiber sensors also.
A high sensitivity humidity sensor based on an Agarose coated photonic crystal fiber interferometer
Show abstract
We report a novel high sensitivity relative humidity (RH) sensor based on Agarose coated photonic crystal fiber
interferometer. We also demonstrate the experimental method to precisely apply a suitable coating thickness to achieve
high RH sensitivity. The sensor shows a linear response for an RH change in the range of 40-70 %RH with a humidity
resolution of 0.03 %RH and a higher humidity resolution of 0.01 %RH in the range 70-95 %RH. The sensor response is
found to be reversible and repeatable with good long term stability.
Comparison of vibration measurements in composite materials using different types of polarimetric sensors
Show abstract
Low frequency vibration measurements in a composite material using embedded polarimetric sensor are presented in this
paper. A glass fiber reinforced composite material sample is fabricated with two different polarimetric sensor types
embedded in it. The two types of polarimetric sensors embedded are based on polarization maintaining photonic crystal fiber
(PM-PCF) and Panda fiber. The vibration frequencies and amplitudes are measured using the embedded polarimetric sensors
and the results from both sensor types are compared. Analysis of the limitations of Panda fiber based vibration measurements
over PM-PCF is carried out and the results are presented. It is found that for high amplitude vibration measurements, PMPCF
based sensors offer a wider linear range and are more suitable than Panda fiber based polarimetric fiber sensors. It is
envisaged that the results from the studies will provide important information to end-users for selecting an appropriate sensor
for vibration measurements in composite materials.
Inline Mach-Zehnder interferometer using liquid filled twin-core photonic crystal fiber with high strain sensitivity.
Show abstract
An inline Mach-Zehnder interferometer (MZI) is demonstrated using liquid filled twin-core photonic crystal fiber (TCPCF).
The TC-PCF is filled selectively with liquid ethanol, increasing the effective refractive index contrast between
twin cores, resulting in interference fringe spectrum with narrower free spectral range (FSR). Strain induced wavelength
shift of the interference fringes is experimentally monitored. Wavelength shifts to the shorter wavelength side with a
sensitivity of about -1.48 pm/με for applied strain change. Selectively liquid filled TC-PCF based MZI is simple to
fabricate and expected to have wide range of applications in optical sensors, multi-wavelength laser source and tunable
optical devices.
Brillouin scattering of a photonic crystal fiber core-offset spliced to a single mode fiber
Show abstract
The Brillouin scattering spectrum of a photonic crystal fiber was measured experimentally by core-offset splicing to a
single mode fiber. One main peak and five sub-peaks due to Brillouin scattering were identified and their frequency and
intensity dependences on strain and temperature were investigated in detail. Besides the frequency shift, the intensity of
the Brillouin scattering was also found to vary with strain and temperature changes. It is then expected to solve the
problem of cross sensitivity in the conventional single-mode fibers.
A Mach-Zehnder interferometer by combining a microtaper with a long period grating in an all solid photonic bandgap fiber and its temperature sensing characteristic
Show abstract
We demonstrate a new type of Mach-Zehnder interferometer by combining a nonadiabatic microtaper with a long period
grating in the same stage of all solid photonic bandgap fibers. Meanwhile, the mode-coupling caused by the microtaper is
indirectly verified by the interference with the long period grating, which is designed for the resonance between the
fundamental core mode and LP01 cladding supermodes. Finally, the temperature response is also reported.
Surface plasmon resonance sensor based on grapefruit fiber filled with silver nanowires
Congjing Hao,
Ying Lu,
Xiangyong Fu,
et al.
Show abstract
We study the surface plasmon resonance sensors based on grapefruit Photonic crystal fiber (PCF) filled with different
numbers silver nanowires. Numerical results show that the intensity sensitivity may be influenced by the distance
between two nanowires and nanowires numbers. A best value is got with a maximum distance of 2μm. And the PCF
filled with more nanowires is better than the one. Moreover, the air holes of grapefruit PCF are large enough to operate
in practice.
Temperature and strain response of Michelson interferometer with asymmetric two-core photonic crystal fiber
Show abstract
We fabricated asymmetric two-core photonic crystal fiber (AS-TC-PCF) and observed the temperature and strain
responses of the Michelson interferometer based on it. The asymmetric two cores induce optical path length difference
and produce polarization-dependent interference fringes. The temperature and strain sensitivities of the AS-TC-PCF
were measured using the interference fringe shift. With increasing temperature, the interference fringes shifted to longer
wavelengths, and the temperature sensitivities were measured to be 5.06 pm/°C and 11.05 pm/°C, respectively, for
different polarizations. However, with increasing strain, the interference fringes shifted to shorter wavelengths, and the
strain sensitivities were measured to be -0.50 pm/με and -1.87 pm/με, respectively.
Strain and temperature sensitivity measurement using simple microstructured fiber Mach-Zhender interferometer
Show abstract
In this paper we present the experimental comparison of mechanical and temperature sensitivities of Mach-Zehnder
interferometer with replaceable FC connectorized sensing fibre arm, such as: off-the-shelf endlessly single mode
microstructured fibre (MSF) or standard telecom single mode fibre. Experimental results clearly show reduced crosssensitivity
to temperature of studied MSF compared with standard doped core fibre. Additionally, microstructured fibre
Mach-Zehnder interferometer with standard FC receptacles allows using different fibres as sensors with the same device.
Moreover, investigated interferometer consumes in total extremely low electric power (< 20 mW) and VCSEL as the
light source.
Dispersion properties of double-clad hollow-core photonic bandgap fibers based on a circular lattice cladding
Show abstract
The major challenges in developing a fiber-optic nonlinear endomicroscope are efficient excitation light delivery and nonlinear optical signals collection, beam scanning, and probe miniaturization [1-4]. Therefore, double-clad PCFs (DCPCF) are used in nonlinear endomicroscope which can play a dual role of ultrashort pulse delivery and efficient collection of nonlinear optical signals [4]. However, due to dispersion of DCPCF, dispersion compensation systems are required. In this paper the dispersion properties and losses of new design of double-clad hollow-core photonic bandgap fibers (DCPBGFs) based on a circular lattice are investigated for the first time, by using a finite difference time domain method.
Birefringence responses of hybrid photonic crystal fiber to strain and temperature
Show abstract
The modal and group birefringence of a hybrid photonic crsystal fiber (Hybird-PCF) and their responses to strain and
temperature are studied theoretically and experimentally. The birefringence properties of a section of Hybrid-PCF
manufactured by University of Bath were measured by using a Sagnac interferometer. The group birefringence, strain
and temperature responsivities of modal birefringence of this Hybrid-PCF were measured to be ~2.5*10-4, 4.39*10-4 (ε-1)
and -1.05*10-7 (ºC-1) respectively. The birefringence properties of Hybrid-PCF can be adjusted by changing the molar
concentration and diameter of its Ge-doped regions.
Photonic crystal fibers as miniature monitoring platforms for petroleum characterization
Show abstract
A fiber design that allows the characterization of high and low refractive index materials is proposed and demonstrated. This fiber consists of an air-silica photonic crystal fiber supporting a Gaussian like mode confined in the fiber core and a ring mode in a region between the structured area and the fiber cladding. This versatile fiber design finds applications in the oil industry where materials of different refractive indices are found. The characterization of petroleum and CO2 using the new fiber is demonstrated.
Surface plasmon resonance sensor based on a novel grapefruit photonic crystal fiber
Show abstract
We propose a novel surface plasmon resonance sensor design based on a grapefruit photonic crystal fiber. In such a
sensor, phase matching between plasmon and a core mode is achieved by introducing microstructure into the fiber core.
Using the finite element method, the confinement loss of the fiber is calculated to measure the sensitivity of the sensor.
Simulation results show that this kind of sensor has an excellent effect, with the amplitude resolution to be as low as
2.88×10-5 RIU and the spectral resolution to be 6.67 ×10-5 RIU.
Selectively infiltrated photonic crystal fibers for strain measurement with ultra-high sensitivity
Y. Wang,
D. N. Wang
Show abstract
An ultrasensitive strain sensor is demonstrated by selectively filling one of the air holes in the photonic crystal fiber.
Light propagated in the photonic crystal fiber core can be coupled to the liquid-filled rod-waveguide efficiently under
phase-matching conditions. The resonant wavelength, which corresponds to the coupling between the fundamental core
mode and the fundamental mode of the adjacent liquid rod waveguide, experiences large shift by applying axial strain.
The experimental results obtained show that the strain sensitivity achieved is ~394.6 pm/με, which is one or two orders
higher than that of conventional fiber gratings.
Thinned fiber based Mach-Zehnder interferometer for measurements of liquid level and refractive index
Show abstract
A novel singlemode-multimode-thinned-singlemode (SMTS) fiber structure based Mach-Zehnder interferometer (MZI) is
proposed for measurements of liquid level and refractive index (RI). We observe that the liquid RI information can be
provided from the sensitivity of the interference peak shifts. Furthermore, by measuring the certain wavelength shift, the
liquid level can be measured accordingly. A 9.00 mm-long thinned fiber with core/cladding diameters of around 4.5/80 μm
is used. The wavelength of 1538.7228 nm exhibits a water level sensitivity of -175.8 pm/mm, and refractive index
sensitivity of -1868.42 (pm/mm) / RIU, respectively. Moreover, the fabrication process is very simple and cost effective.
Multiplexed localized surface plasmon resonance sensing with suspended core fibers
Show abstract
Sensors based on the localized surface plasmon resonance (LSPR) effect are known as sensitive methods for refractive
index measurements or for detection of specific binding reactions in biosensing due to a variation in layer thickness.
Fiber based arrangements are able to perform such measurements with very small analyte volumina. A generalization of
this concept for a multiplexed measurement of different biomolecules in a single fiber could be an attractive approach.
We discuss the possibility of selectively sensitizing the inner surfaces of a suspended core fiber with two different
metallic nanoparticle types in monolayers for such multiplexed measurements.
Principle of the temperature sensor based on two mode nano-wire Silicon-on-Insulator waveguides
Show abstract
A prototype of the temperature sensor based on the nano-wire Silicon-on-Insulator (SOI) waveguides, with air cladding
or SiO2 cladding, is proposed with the principle of two mode interference (TMI) in the two mode nano-wire SOI
waveguides. The beatlength, between the two modes with same polarization in the two-mode regime, are shown with the
dependence on the waveguide parameters. The effects of the birefringence on the temperature sensor are discussed.
In-line single-mode fiber interferometers based on peanut-shape fiber structure
Show abstract
A novel peanut-shape fiber structure which can realize the coupling and re-coupling between the fiber core mode
and the cladding modes is proposed in this paper. Based on the peanut-shape structure, two kinds of simple and
low-cost interferometers are fabricated in single-mode fiber (SMF). Experimental results show that the temperature
sensitivities of the Mach-Zehnder and Michelson interferometers were ~46.8pm/°C and ~0.096 nm/°C, respectively.
In particular, the Michelson interferometer could be heated up to 900°C, which is suitable for the high temperature
sensing applications.
Sensing characteristics of tapered high-birefringent optical fiber
Show abstract
A high-birefringent fiber (HBF) was tapered as adiabatic in sequence steps by utilizing a CO2 laser and its birefringence
was measured in fiber loop mirror (FLM) setup. The birefringence of tapered section and total sensor was obtained to be
-8.02×10-2, and 2.46×10-4, respectively. Then, refractive index (RI) sensitivity increased and temperature sensitivity of
the tapered Hi-Bi fiber (THBF) decreased. The sensitivity of the proposed FLM interferometer for RI changes in the
range from 1.3380 to 1.3470 was measured to be 389.85 nm/RIU. The temperature sensitivity in the range from 50°C to
90 °C was measured to be -1.19nm/°C.
A fast-response microfiber coupler tip high temperature sensor
Show abstract
A compact fast temperature sensor based on a broadband microfiber coupler tip is demonstrated. The thermometer
dynamic range spans from room temperature to 1511 °C with a response time of tens of ms. This is the highest
temperature measured with an optical fiber device. The resolution of 0.66 °C was achieved for a coupler tip diameter of
~12.56 μm.
Spectral bandwidth analysis of high sensitivity refractive index sensor based on multimode interference fiber device
Edwin G. P. Pachon,
Marcos A. R. Franco,
Cristiano M. B. Cordeiro
Show abstract
Fiber optic structures based on multimode interference were investigated to the refractive index (RI) sensing. The
proposed device is a singlemode-multimode-singlemode (SMS) structure, where the multimode section is a coreless fiber
(MMF). The numerical analyses were carried out by beam propagation and modal expansion methods. Ultra-high
sensitivity was obtained: 827 nm/RIU over a RI range of 1.30-1.44 and a maximum sensitivity of 3500 nm/RIU for
RI~1.43, considering ▵RI = 0.01. The dependence of spectral bandwidth was investigated taking into account the
multimode fiber diameter and the coupling efficiency between modes at the input junction singlemode-multimode.
Optical fiber hydrogen sensor based on micro interferometer
Show abstract
In this paper, a femtosecond (fs) laser fabricated fiber in-line micro Michelson interferometer (MI) with palladium (Pd)
film deposited on the fiber end face for hydrogen detection is proposed and demonstrated. Beam Propagation Method
(BPM) is used to analyze the influence of refractive index (RI) of Pd film on reflection spectrum. As for the
experimental results, the variation of optical power and shift of interference peak wavelength are -4.904 dBm and -4.2
nm respectively with the increase of hydrogen concentration from 0% to 16%. The developed system has high potential
in hydrogen sensing with high sensitivity.
FBG-microfiber-FBG cascade Fabry-Perot interferometer for simultaneous measurement of temperature and refractive index
Show abstract
A microfiber Fabry-Perot interferometer (FPI) which employs two fiber Bragg Gratings (FBGs) as reflection mirrors and
a short length microfiber as its cavity is proposed and fabricated. Theoretic study shows that the reflection spectrum of
such microfiber FPI is consisted of two parts - interference fringes induced by FPI and reflection band induced by FBGs.
Temperature affects both parts while ambient refractive index only influences the first part, i.e. microfiber FPI has
different response to temperature and RI. Therefore, Dual-parameter measurement is experimentally demonstrated by
tracking the FSR variation and the central wavelength shift of the reflection spectrum of microfiber FPI.
Temperature sensor by using alcohol-filled side-hole fiber based Sagnac interferometer
Show abstract
A temperature sensor by using an alcohol-filled side-hole fiber (SHF) based Sagnac interferometer is proposed and
experimentally demonstrated. The alcohol liquid is filled into air holes of the SHF. Due to its temperature-dependent
refractive index, interference pattern of the Sagnac interferometer shifts at sensitivity of 86.1 pm/°C when temperature is
changed in a range between 20°C and 70°C.
High sensitivity temperature sensor using microfiber based Mach-Zehnder interferometer
Show abstract
A high sensitive temperature sensor based on Mach-Zehnder interferometer (MZI) is proposed and experimentally
demonstrated. Temperature measurement is achieved by immerging a section of microfiber into the refractive index (RI)
liquid with a high thermo-optic coefficient. A slight change of ambient temperature will lead to the enhanced variation
of the liquid index. Due to the evanescent field of microfiber, microfiber effective refractive index will be changed, and
subsequently the optical length. Thus, by measuring the free spectral range (FSR) of the MZI, the temperature sensor can
achieve a high sensitivity of 6.44nm/°C at the temperature of 20.6°C.
Temperature-independent refractive index sensor based on a Bragg grating in highly birefringent microfiber
Show abstract
We demonstrated a novel method for temperature-independent refractive index measurement by use of a Bragg grating
fabricated in a highly birefringent rectangular microfiber. The two reflective peaks corresponding to two polarization
axes exhibit almost identical temperature sensitivity of 12.01 pm/°C and different responses to ambient refractive index
of 38.9 and 46nm/RIU at RI of 1.36, respectively. By monitoring the wavelength separation between the two peaks,
temperature-independent refractive index measurement can be achieved.
In-fiber microsphere air-cavity Fabry-Perot interferometer for strain/temperature measurement
Show abstract
A novel in-fiber microsphere air-cavity Fabry-Perot interferometer (FPI) sensor is constructed and demonstrated
for strain and temperature measurement. The microsphere air-cavity is formed by ablating, with a focused femtosecond
infrared laser, the endface of a single mode fiber (SMF) to form a crater at its center, and then splices this fiber end to a
second SMF using a fusion splicer. The sensor demonstrates a strain sensitivity of 2.44 pm/με and a low temperature
sensitivity of 0.87 pm/ºC up to 600 ºC.
Fiber Bragg gratings in few-mode highly birefringent microstructured optical fibers for sensing applications
Show abstract
In this paper we present the results of theoretical characterization of a few-mode birefringent microstructured fiber
dedicated for fiber Bragg grating (FBG) inscription. The spectral characteristics of FBGs written (with a nanosecond and
femtosecond laser Talbot interferometer setups) in the core region of the investigated fiber are presented and discussed.
We compare the experimental results of the polarimetric strain sensitivity with our previously reported data, outlining
perspectives for developing a highly sensitive (with strain sensitivity of second order mode two orders of magnitude
higher in comparison to fundamental mode), temperature independent, FBG based strain transducer.
An investigation of the polarization dependence of a temperature sensor based on an optical microfiber coupler
Show abstract
The dependence on polarization of the performance of a microfiber coupler based temperature sensor is
experimentally investigated. The optical microfiber coupler based temperature sensor has a diameter circa 2 μm and can
sense temperature in the range from 100°C to 1000°C, with an average sensitivity of 18.9 pm/°C. It is shown that
different polarization states of the input signal have a significant influence on the proposed temperature sensing
accuracy, with an estimated peak error of 63°C at 1000°C.
Monitoring of fluid evaporation using fiber-optic micro-cells
Eyal Preter,
Borut Preložnik,
Chaim N. Sukenik,
et al.
Show abstract
The monitoring of fluid evaporation from within fiber-optic micro-cells is proposed and demonstrated. The evaporation
process is accompanied by a pronounced temporary attenuation in the transmission of light through the micro-cell, by as
much as 50 dB. The temporal attenuation profiles observed for acetone, ethanol and hexane are distinctly different.
Temporal attenuation measurements can therefore allow for the identification of fluids based on their physical properties,
rather than their refractive indices. The evaporation of fluid mixtures is monitored as well.
Fiber taper sensors fabrication with arbitrary profiles using a modified flame-brush approach
A. Felipe,
G. Espíndola,
Y. Wang,
et al.
Show abstract
This work reports a method to fabricate fiber taper sensors with arbitrary profiles. It is based on the approximation
of the desired taper profile function by a series of step functions. As a consequence, monotonic taper
transition profiles can be constructed with a number of flame-brush passes, each one supposedly producing a
stepwise uniform reduction of the fiber diameter. Differently from what is done in other methods, constant speeds
in all the translation stages are used in the process. A non-symmetrical arbitrary taper profile was fabricated in
a singlemode fiber to demonstrate the feasibility of the method.
Raman detection of hydrogen peroxide in suspended core optical fibers
Show abstract
The first demonstration of a detection scheme for hydrogen peroxide based on Raman spectroscopy in suspended core
optical fibers is presented. This detector combines the advantages of Raman spectroscopy, such as the unique
identification of a molecular fingerprint, with a microstructured fiber architecture, which enables low volumes
processing and detection. Hydrogen peroxide is chosen as a target molecule since it is a key component in home-made
explosives. These results highlight the feasibility of the proposed scheme as a low false-positive detection platform.
Controlling the fabrication of self-assembled microwires from silica nanoparticles
Show abstract
We report on recent advances made in fabricating photonic microwires from silica nanoparticles using evaporative self-assembly. Silica microwires up to 7 cm in length and widths as small as 10 µm were fabricated with rectangular cross sections. A model of fabrication is put forward and confirmed by experimental observation. A crude dependence on concentration for an idealised spherical droplet is explored.
In-line fluidic absorption coefficient sensor based on optical microfiber
Show abstract
An in-line fluidic absorption coefficient sensor based on the optical microfiber (OM) is proposed. We calculate the
insertion loss of the OM per millimeter after immerged into liquid with various absorption coefficients. Then a 1.8μm
diameter OM with 10 millimeters uniform waist region is used to analyze the absorption of pure water, and the
absorption spectrum from 1525nm-1565nm is achieved from the experiment, agreeing well with the reported absorption
coefficient. The in-line fluidic absorption coefficient sensor has potentially wide sensing range by controlling the
construction of OM for many kinds of absorptive liquids with lower refractive index than silica.
Spectral tuning of a microfiber coupler with a liquid crystal overlay
Show abstract
This paper demonstrates temperature-induced tuning of the optical spectrum of a microfiber coupler covered with a low-refractive
index liquid crystal (LC) layer. The microfiber coupler with a minimum waist diameter of ~6 μm is fabricated
by fusing together and tapering of two standard telecom fibers using a microheater brushing technique and by placing a
thin heated LC layer over the uniform taper waist region. Repeatable and reversible tuning of the optical spectrum
(~4 nm) of the microfiber coupler is demonstrated for the temperature range of 50-78 °C.
A high-speed and high-precision phase-shift demodulation algorithm for optical fiber sensing system based on low-coherence interference
Show abstract
A novel demodulation algorithm, comprising of a calibration algorithm and improved linear fitting phase-shift algorithm,
is proposed for optical fiber sensing system based on low-coherence interference. The calibration algorithm is used to
identify the fringe order. Traditional phase-shift algorithm is improved to get the linear fitting curve of the relative phase
corresponding to zero-order fringe and the peak position is retrieved from its zero point. Comparing with Fourier based
algorithms, the computation of proposed algorithm is small (approximately 25 times faster) while sustains high precision
with 2nm maximum error of cavity length. Experiments were carried out to verify the performance.
A highly sensitive and fast response molecular sensor based on graphene coated microfiber
Show abstract
Graphene's featureless optical absorption, ultrahigh carrier mobility and optical modulation capacity would enable a new
breed of optical devices with novel photonics characteristics. The complex refractive index (CRI) of graphene can be
modulated by its local boundary conditions when molecules are attaching on the surface of the graphene layer, leading to
change in the CRI of graphene, which would induce altered properties of the evanescent wave propagating between the
graphene film and optical waveguide. In this paper, a novel fiber-optic sensor concept that integrates the graphene film
onto a microfiber is proposed to detect the molecular concentration based on TE intensity measurement. The theoretical
investigation shows that such a sensor could offer a solution for realization of a variety of high sensitivity and fast
response molecular sensing in biological, medical and chemical fields.
Laser-machined cascaded micro cavities for simultaneous measurement of dual parameters
Zengling Ran,
Cheng Li,
Min Ni,
et al.
Show abstract
Fiber-optic cascaded micro Fabry-Perot (F-P) cavities fabricated by 157-nm laser micromachining is demonstrated, for
simultaneous measurement of high temperature and refractive index, or high temperature and strain, respectively. The
sensor head consists of a short air extrinsic F-P cavity and an intrinsic single-mode fiber F-P cavity. These two micro
cavities possess different response coefficients to temperature, stain and refractive index, which are ultilized for dual
parameters measurement. Experimental results shows dual parameters meausurement could been achived from 50℃
~380℃ based on such a sensing structure.
Lab on fiber using self assembly technique: a preliminary study
Show abstract
In this work, we report the preliminary results on the fabrication of metallo-dielectric nanostructures on the optical fiber
tip by using a simple and low cost self-assembly approach. The fabrication process relies on the breath figure technique
here adapted to operate on unconventional substrates as the case of single mode optical fibers. The experimental results
demonstrate the successful creation of a honeycomb pattern on the optical fiber tip and the feasibility of the proposed
approach in the roadmap of "Lab on fiber" technology development. Further work is currently running aimed to the
assessment the presented fabrication procedures in order to attain advanced optical fiber sensing probes with high
fabrication throughput by exploiting a low cost technology.
Sensing properties of intrinsic Fabry-Perot interferometers in fiber tapers
Show abstract
A sensing configuration of the fiber taper intrinsic Fabry-Perot interferometer (FTIFPI) was presented and developed.
Direct inscription method of intrinsic Fabry-Perot interferometers in optical fiber tapers with a femtosecond laser has
been fabricated experimentally. Fabry-Perot interferometers are firstly realized in the waist of fiber tapers. The
experimental results indicate that the change in wavelength has a good linear relationship with temperature, while the
fringe visibility keeps the same approximately. In the range of 0°C~100°C, the interference spectrum sensitivity is
12pm/°C. The fringe visibility decreases linearly with the liquid refractive index increasing, while extremes keep the
same approximately.
Noise analysis and optimization for PGC method
Show abstract
We analyze the transfer factor for phase noise (NTFφ) of PGC system. According to NTFφ , we optimize the system
phase noise performance by setting proper working point. Since we use hydrophones with the same Distributed
Feedback (DFB) laser, the noise from laser resource takes the leading post. We build up the theory model of correlation
coefficients, and demonstrated a new system using a reference interferometer with 32 coupler. The homologous noise is
eliminated. We get output noise with the PSD (Power Spectral Density) 8.5dB higher than that of circuit noise and 14dB
higher than that of DC intensity noise.
Interrogation of remote intensity-based fiber-optic sensors deploying delay lines in the virtual domain
Show abstract
In this work a self-referencing intensity-based fiber-optic sensor using virtual instrumentation is presented. The use of
virtual delay lines along with novel self-referencing techniques minimizing resolution and using a single frequency
avoids all-optical or electrical-based delay lines approaches at reception. This solution preserves the self-referencing and
performance characteristics of the proposed optical sensing topology, and leads to a more compact solution with higher
flexibility for the multiple interrogation of remote sensing points. Results are presented for a displacement sensor
demonstrating the concept feasibility.
Resilient optical fiber ladder network with OADMs to multiplex sensors: experimental validation of binary state connectivity analysis
Show abstract
We experimentally demonstrate a resilient wavelength division multiplexed (WDM) fiber ladder network, based on
optical add-drop multiplexers (OADMs), to interconnect sensors. It recovers operation after failures and it enables "selfdiagnosis",
the identification of the failed element(s) from the patterns of surviving end-to-end connections at all
operating wavelengths. A theory for such topologies, the "binary state connectivity analysis", used a matrix formalism to
predict the surviving channels at the receiver node after damage occurs in one or more sites. We present experimental
measurements for double failures in the network, demonstrating complete agreement with theoretical predictions.
Investigation on the scale of DFB fiber laser sensor array limited by coherence collapse
Show abstract
The influence of coherence collapse due to Rayleigh backscattering on the scale of DFB fiber laser sensor array is
investigated. The largest scales of a two-element sensor array and a three-element sensor array are measured to be 160 m
and 250 m. Results indicate that coherence collapse due to Rayleigh backscattering does not limit the multiplexing
capability of DFB fiber laser sensor array when the multiplexing capacity remains to be several tens, which is significant
for the scale extension of DFB fiber laser sensor array.
BOTDA sensor network with power by light remote switching
Show abstract
We present and demonstrate a Brillouin Optical Time Domain Analysis (BOTDA) based long range sensor network with
remote switching. Two different 5 km long sections were monitored alternatively by using a fast remotely controlled and
optically powered up optical switch. The sensed fibers were located 10 km away from the interrogation unit. The
BOTDA unit uses a simplified configuration to reduce the sensor network costs. Proof-of-concept experiments were
carried out verifying the capacity of the proposed system.
Remote resilient FBG multiplexing network controlled by a powered by light fiber optic switch
M. Bravo,
M. A. Erro,
J. M. Algueta,
et al.
Show abstract
In this work, a remote powered by light fiber optic switch is experimentally demonstrated. This fiber optic switch is
powered by a photovoltaic power converter illuminated by a Raman laser working at distances up to 50 km. This
switch is used to develop a remote resilient FBG multiplexing network interrogated by a commercial FBG
interrogator. In the proposed set-up the switch selects the branch of the FBG network 50 km away in order to enable
a two-way interrogation path for each sensor to prevent connection failures.
Interferometric time division FBG interrogator and multiplexer with static, dynamic, and absolute wavelength measurement capabilities
Show abstract
We report on the design and preliminary testing of an interferometric interrogator capable of large-scale time-division
multiplexing of FBG sensors. The scheme employs a passive algorithm for phase demodulation, allowing changes in
FBG sensor reflected wavelengths to be calculated instantaneously upon arrival, and incorporates a technique for
identification of initial absolute sensor wavelengths in order to overcome the measurement ambiguity associated with
interferometric schemes. The proposed system will allow for high-speed interrogation of large-scale FBG sensor arrays
with interferometric resolution and the capability for dynamic, static, and absolute FBG wavelength measurement.
High performance fibre-optic acoustic sensor array using a distributed EDFA and hybrid TDM/DWDM, scalable to 4096 sensors
Show abstract
An amplified 16 channel dense wavelength division multiplexing (DWDM) array architecture is presented for
interferometric fibre optic sensor array systems. This architecture employs a distributed Erbium doped fibre amplifier
(EDFA) scheme to decrease the array insertion loss, and employs time division multiplexing (TDM) at each wavelength
to increase the number of sensors that can be supported. The first experimental demonstration of this system is reported
including results which show the potential for multiplexing and interrogating up to 4096 sensors using a single telemetry
fibre pair with good system performance.
Range-resolved single-sideband optical fibre interferometry for quasi-distributed dynamic strain sensing
Show abstract
A novel optical signal processing scheme for fibre sensors is proposed, which combines interferometric phase
measurements with range multiplexing. The scheme is based on single-sideband signal processing and uses continuous-wave
pseudo-random range encoding. The potential of the technique for cost-effective dynamic quasi-distributed strain
sensing is explored by applying it to an array of fibre segments. In its current implementation dynamic strains in
segments of 3.4 m gauge lengths can be measured with a resolution well below microstrains at a bandwidth of 100 kHz.
200-km long fiber ring laser for multiplexing fiber Bragg gratings arrays
Show abstract
This work proposes and demonstrates a 200 km long distance fiber ring laser for multiplexing arrays of FBGs. Unlike
previous long distance reported fiber lasers, the system in based on a ring cavity which involves that the amplified
transmitted signal travels in a different fiber than the signal reflected by the FBGs. This fact helps to avoid the most
limiting factors when the distance between the sensor and the processing unit needs to be increased. To our knowledge,
this is the longest reported fiber laser system with remote sensing capability; it is also able to multiplex 7 fiber Bragg
gratings, while previous ultra-long systems only multiplex up to 4. In addition, due to the mode operation of the system,
it is a low noise configuration, thus the OSNR of all the sensors is high enough to interrogate them 200 km away from
the monitoring station.
Wavelength division multiplexing technique for grating panel-based fiber optic sensor
Show abstract
Optical fibers can be used as promising sensors in smart structures due to their novel characteristics. This paper presents
a wavelength division multiplexing (WDM) technique in order to improve the application capacity of single reflective
grating based fiber optic sensors to monitor large industrial structures at multiple points. The models are appropriate for
the general extrinsic fiber optic sensors such as the grating panel-based fiber optic sensor. The manufactured WDM fiber
optic sensor system was examined in order to demonstrate the feasibility for two parameter detections at two points using
mirror mounted grating based fiber optic sensor.
Dynamical strain sensing via discrete reflectors interrogated by optical frequency domain reflectometry
Oren Y. Sagiv,
Dror Arbel,
Yinon Katz,
et al.
Show abstract
Dynamical sensing of strain via discrete reflectors interrogated by optical frequency domain reflectometry is described
and demonstrated experimentally. The benefits of using discrete reflectors rather than Rayleigh back-scattering for
dynamical measurements are elaborated. The method is tested in a sensor arm made from four discrete fiber segments of
different lengths and in a fiber with an array of ten fiber Bragg gratings with the same center wavelength and ~0.5%
reflection. Dynamical sensing of oscillatory strain at 100 Hz, with absolute stretching amplitude <100nm, at ~1km is
demonstrated.
Poster Session 3: Fiber Optic Gyroscopes, New Fibers and Coating Materials, Distributed Sensing, Sensor cont.
Hybrid linear and circular polarization Er-doped fiber ring laser gyroscopes
Show abstract
A bidirectional single-longitudinal-mode Er-doped fiber ring laser was proposed. Based on it, a fiber laser gyroscope was
demonstrated. With circularly polarized lights in the Er-doped fiber, and linearly polarized lights in the rest part of the
ring, a reciprocal structure was obtained, and the spatial hole burning effect was suppressed. In the experiments, the
lock-in threshold rotation rate was 6 o/s. When the rotation rate was beyond 6 o/s, a beat RF signal of over 30-dB noise
was observed and a good linear relation between the beat frequency shift and cavity rotation rate were obtained. Finally,
the beat frequency stability was tested for 20 o/s clockwise cavity rotation.
Design in depolarized FOGs using effective model and genetic algorithm
Show abstract
This study combines the methods of the Stokes parameters and genetic algorithm (GA) with the mathematical model
in the depolarized fiber optic gyroscope (FOG) for finding the optimal structure of FOG. An effective model to simulate
a SM fiber coil and genetic algorithm for finding minimum bias errors are proposed for solving the problems of
polarization errors and signal-fading in the depolarized FOG. As a result of analysis in model, the minimum bias error
can be found as 4.4×10-5 °/hour with 1000 m in length of the fiber coil. As the authors' knowledge, this is the first idea in
simulating the effective parameters of a SM fiber coil and using GA in finding the optimal structure for the depolarized
fiber optic gyroscope.
Radiation resistant fibers with depressed claddings for fiber optic gyro sensing coil
A. M. Kurbatov,
R. A. Kurbatov
Show abstract
A two kinds of single mode optical fiber are described: three-layer with depressed fluorine clad (W-fiber) Panda
with Nitrogen core, and isotropic fiber with pure (undoped) quartz core and two fluorine claddings (narrow and wide).
Both of these fibers could be used in fiber optic gyro sensing coil operating in space radiation environment.
Frequency noise characteristics of a narrow-linewidth DFB semiconductor laser in resonator fiber optic gyro
Show abstract
It is important to study the frequency noise of the laser characteristics in a resonator fiber optic gyro. A measurement of
the power spectral density of optic frequency noise is introduced into a resonator fiber optic gyro. An optic optimum
criterion for the frequency stabilization loop of the resonator fiber optic gyro is proposed, especially for the reduction of
the locking residual error and the widening of the gyro bandwidth.
Advanced techniques for evaluating the quality of fiber gyro coils
Zhuo Meng,
X. Steve Yao,
Zhihong Li,
et al.
Show abstract
We present several advanced techniques for evaluating the quality of fiber gyro coils, including characterizing the
temperature and vibration transient characteristics of fiber coils, monitoring polarization-maintaining fiber (PMF) coil
winding quality using distributed polarization crosstalk analyzer (DPXA) during production, and the defect detection of
fiber coil using optical coherence tomography (OCT). To the best of authors' knowledge, this is the first report of using
OCT for fiber coil inspection. The use of these new techniques can effectively improve and guarantee the quality of the
fiber gyro coils.
Optimization of frequency stabilization loop for resonator fiber optic gyro
Show abstract
A frequency stabilization loop based on the proportional integrator is used in the resonator fiber optic gyro. Proper loop
parameters are important to the reciprocal noise suppression, the response speed improvement and loop stabilization. The
loop parameters such as the time constant of the low-pass filter, the loop gain, the integration time and the loop delay are
analyzed deeply and then optimized. A rotation result of ±0.05°/s has been carried out.
Dependences of Brillouin frequency shift on strain and temperature in optical fibers doped with rare-earth ions
Show abstract
Brillouin scattering properties in rare-earth-doped fibers, including Nd3+-doped, Tm3+-doped, Sm3+-doped, and
Ho3+/Tm3+ co-doped fibers, can potentially be controlled at high speed by pumping, but there has been no report on their
detailed investigations. In this study, the Brillouin gain spectra (BGS) in such rare-earth-doped single-mode fibers are
measured, for the first time to the best of our knowledge, at 1.55 μm without pumping, and the Brillouin frequency shift
(BFS) and its dependences on strain and temperature are investigated. Clear BGS was observed for the Nd3+-doped and
Tm3+-doped fibers, but BGS was not detected for the Sm3+-doped and Ho3+/Tm3+ co-doped fibers probably because of
their extremely high propagation losses at 1.55 μm and small Brillouin gain coefficients. The BFS of the Nd3+-doped
fiber was ~10.82 GHz, and its strain and temperature coefficients were 466 MHz/% and 0.726 MHz/K, respectively. As
for the Tm3+-doped fiber, the BFS was ~10.90 GHz, and its strain and temperature coefficients were 433 MHz/% and
0.903 MHz/K, respectively. These measurement results are compared with those of silica fibers.
Polarization-maintaining fiber with wide temperature resistance
Show abstract
We have developed a polarization-maintaining fiber with wide temperature resistance and low bending loss. Attenuation,
polarization crosstalk, and bending loss at 1550 nm of the fiber are 0.88 dB/km, -24 dB/100m, 1/100 as large as those of
conventional one (bending diameter = 20 mm, 10 turns), respectively. Besides, the polarization crosstalk is less than -24
dB/100m at a temperature in the range of -60 to +300oC. As a result this fiber can be used over a wide range of
temperature.
Development of a sensitive fiber optic sensor monitoring NO based on vicinal diaminobenzoacridine fluorophore
Show abstract
A new fiber optic sensor has been developed for determination of NO using a fluorescent vicinal diaminobenzoacridine
(VDABA) probe. The sensitive membrane was prepared from cellulose acetate (CA) embedded with VDABA, which caused
a fluorescence recovery based on a photoelectron transfer (PET) mechanism. Modulation of optical phase shift of the sensor
is observed with different NO concentrations. Under optimum conditions, a linear calibration (r2=0.9902) was obtained in the
range of 1.0×10-8 to 1.0×10-5 mol/L NO concentration with a detection limit of 1.0×10-9 mol/L (S/N=3). This sensor was
successfully applied to the determination of NO in the rabbit serum.
Brillouin frequency shift dependences on temperature and strain in PMMA-based polymer optical fibers estimated by acoustic velocity measurement
Show abstract
We estimated the dependences of Brillouin frequency shift (BFS) on temperature and strain in poly(methyl
methacrylate)-based polymer optical fibers using ultrasonic pulse-echo technique at ~10 MHz. The estimated BFS
dependence on temperature was linear with a coefficient of approximately -17 MHz/K at 650 nm pump, which was -34
times larger than that of silica fibers at 650 nm pump. In contrast, its strain dependence was found to be nonlinear,
probably originating from the elastic-to-plastic transition.
Theoretical and experimental analysis of the birefringence in embedded-core hollow optical fibers
Show abstract
We propose a novel embedded-core hollow optical fiber composed of a central circular air hole and a semi-elliptical core
embedded in an annular cladding. Both the phase birefringence and group birefringence are investigated based on the
finite element method (FEM). The embedded-core hollow optical fiber has polarization-preserving properties. The
birefringence magnitude of the proposed fibers is the same order as that of the side-hole optical fiber. The theoretical
results reveal that the birefringence of embedded-core hollow optical fibers can reach the order of 10-4. The group
birefringence of the fiber is obtained by using the wavelength scanning technique and can reach 4.7×10-5. The
measurement results are basically consistent with the theoretical simulations.
Fabrication of coaxial dual-waveguide structured optical fiber with an annular waveguide layer
Show abstract
A coaxial dual-waveguide structured optical fiber with an annular waveguide layer (CDOF) is designed and its
preparation method is provided thereof. The responding preform is fabricated by MCVD technique and then is drawn by
a custom-made fiber drawing tower. The optical fiber has a common fiber core and an annular waveguide layer on the
outer surface of the optical fiber. The refractive index profile is measured by a refracted near-field technique and a
standard cutback technique. The fiber can be applied in a novel optical fiber device or an optical fiber sensor, for
example, in-fiber integrated Michelson or Mach-Zehnder interferometer.
Design of a novel quasi-Airy beam generator: Airy optical fiber
Show abstract
We report and demonstrate a novel quasi-Airy beam generator based on a microstructured optical fiber: Airy optical
fiber. We show that the three Airy beam characteristics are inherited or partially inherited for the output optical beam
from the Airy optical fiber end, i.e. the ability of beam accelerating, beam diffraction-free and self healing. The
simulation results are agreement with the theoretical analysis of the theoretical model.
A wavelength division multiplexer based on a cocentric core fiber
Show abstract
We report and demonstrate a new type of fiber wavelength division multiplexer based on central-circular cocentric core
fiber. Using splicing technique to connect the central-circular cocentric core fiber and single mode fiber, then, tapering at
the fusion point of two fibers. The light source whose wavelengths are 980nm and 1480nm input from the single mode
fiber, then two wavelengths transferred separate well at the tapering area of the cocentric fiber. The simulation results are
agreement with the theoretical analysis of the theoretical model.
An integration strain sensor based on symmetrical twin-core fiber
Show abstract
A novel integrated fiber-optic sensor based on a symmetrical twin-core fiber was proposed and demonstrated as a strain
sensor. By heating and tapering the symmetrical twin-core fiber, the light from one core can be partly or completely
coupled into the other core in the coupled zone as the twin-core fiber was pulling. By detecting the output power of any
one core, the strain applied on the twin-core fiber can be detected. The output power of twin core fiber versus the applied
strain was experimentally investigated, and the results showed that the twin-core fiber can be used as a strain sensor.
Input-polarization-induced phase noise in interferometric fiber-optic sensors and its reduction using polarization diversity receivers
Show abstract
The random fluctuation in the input polarization to an interferometric optical fiber sensor can result in not only the
variation of the visibility but also the generation of excess phase noise in the output. In this paper, the relationship
between the visibility and polarization-induced phase noise coefficient is described and theoretically confirmed. The use
of polarization diversity receivers (PDR) to reduce phase noise is theoretically and experimentally demonstrated. The
result shows that the PDR that improves the visibility can reduce the polarization-induce phase noise and the signal can
be correctly demodulated.
Photonic generation of microwave signal using a dual-wavelength fiber ring laser with CMFBG filter and saturable absorber
Show abstract
A simple approach for photonic generation of microwave signal using a dual-wavelength single-longitudinal-mode
erbium-doped fiber ring laser is proposed and demonstrated. For the first time, a chirped moiré fiber Bragg grating
(CMFBG) filter with ultra-narrow transmission band and a chirped fiber Bragg grating are used to select the longitudinal
mode. The stable single longitudinal mode operation is guaranteed by the combination of the CMFBG filter and 3m
unpumped erbium-doped fiber acting as a saturable absorber. Stable dual-wavelength single longitudinal mode fiber
laser with a wavelength spacing of approximately 0.140nm are experimentally realized. By beating the dual-wavelength
fiber laser at a photodetector, photonic generation of microwave signal at 17.682GHz is successfully obtained.
Superstructured FBG based optical encoder/decoder for highly-confidential 40 Gbps telecommunication network
Show abstract
40 Gbps optical encoding/decoding is demonstrated utilizing 8-level phase codes, 8 grating chips and 2.6 mm long
superstructured fiber Bragg grating (SSFBG). Novel refractive index profile is applied to the SSFBG to obtain highlyrecognizable
performance of encoding signal and highly-confidential decoding signal. Time-spreading optical codes are
clearly observed from the encoding signals, and over 13 dB power contrast ratio is confirmed from the decoding signals.
Dual-π-phase-shift distributed feedback fiber laser for strain sensing
Show abstract
A dual-π-phase shift distributed fiber laser (DFB FL) with symmetric structure is investigated as a strain sensor. The
sensing performances under both monolithic and local axial strain are discussed by use of transfer matrix method. While
the two lasing wavelengths of dual-π-phase shift DFB FL experience the same change as that of single-η-phase shift
DFB FL under monolithic strain, their wavelength interval changes with local strain. And the strain sensitivity of beat
frequency is calculated to be 70.6 MHz/με while one phase shift area is insensitive.
Noise floor analysis of the phase demodulation scheme using a 3×3 coupler
Show abstract
The noise floor of the phase demodulation scheme using a 3×3 coupler was analyzed, where the signal was demodulated
by linear combination of the three outputs and digital inverse arctangent approach. According to our study, the noise
floor has connection with the noise intensity, noise correlation and initial phase. The approximate expressions to
calculate the noise floor were deduced and validated by simulations with input Gaussian white noise. Experiment results
show that the predicted noise floor distribution as a function of initial phase agreed well with the experiment results. The
noise floor of the experiment system was below 0.70 μrad/√Hz@1kHz.
Light power sensor by using a photosensitive liquid crystal hybrid film on side polished fiber
Show abstract
A novel light power sensor is demonstrated by using side polished fiber (SPF) overlaid with a photoresponsive
liquid crystal hybrid film. The mixture of 15%Azo, 20% ZLI811, and 65% nematic liquid crystal is overlaid on the flat
area of SPF to form a mixture film of ~30m thickness. The film is irradiated by light of wavelength of 405nm through a
phase mask with a period of ~528nm. An absorption peak in the transmission spectrum of 1520-1620nm of optical fiber
is observed. Experiment shows that the wavelength of absorption peak will shift toward shorter wavelength as the
irradiation power increases. The change of wavelength of absorption peak is approximately linear to the irradiation
power while the irradiation powers are between 30-80mw in our initial experiments. The measured sensitivity of light
power is about 1.154pm/uW for the demonstrated sensor.
Wide range group delay tuning in lossy fiber ring resonators
Show abstract
We demonstrate theoretically and experimentally that a wide-range tuning of group delay values can be achieved in a
lossy fiber ring resonator. The tuning mechanism relies simply on varying the loss/coupling ratio in the resonator. This
simple structure may be used advantageously in different regimes for many sensing configurations, both for achieving
extremely high sensitivity enhancements (by working close to critical coupling, where the group index becomes
extremely large) or suppression of undesired refractive index effects (e.g. Kerr effect), by working in the under-coupled
regime.
Individual or simultaneous temperature and strain monitoring by high birefringence fiber loop mirror with reduced cross sensitivity
Show abstract
Individual or simultaneous monitoring of the temperature and strain variations by use of the high birefringence fiber loop
mirror is newly proposed and demonstrated with reduced cross sensitivity. It is accomplished by incorporating two types
of high birefringence fibers in the loop arm, which are spliced together to act as the compact sensing head. By properly
choosing their birefringence, cutting their lengths and setting their relative orientation with respect to the primary axes,
the temperature and strain may be individually or simultaneously measured with the effectively reduced cross sensitivity.
Integral temperature hybrid laser sensor
Show abstract
An integral temperature sensor based on Brillouin laser ring that is feed by a Fourier Domain mode-locking (FDML)
laser is here proposed. The source FDML laser ring emits at 1532 nm within a range of 5 nm. The working wavelength is
given by tuning the offset voltage applied to a Fabry-Perot tunable filter (FFP-TF). In the present work, the FDML laser
linewidth is set at 0.136 nm. This linewidth allows a more efficient Brillouin response in the optical fiber without
increasing the Brillouin threshold. The FDML laser linewidth is controlled by setting the amplitude modulation of the
drive signal offset applied on the FFP-TF.
Distributed pressure measurement by Brillouin scattering dynamic grating for a two side holes fiber
Show abstract
In some of the optical fiber pressure sensors, the pressure on the fiber is converted to the strain along the fiber by a
mechanical transducer and the strain is measured. As the transducer causes many limitations in sensing process, we used
stimulated Brillouin scattering generated dynamic grating for distributed measurement of direct pressure without any
transducer in this paper. The sensitivity of the dynamic grating characteristic to the pressure loaded on the fiber for a two
side holes fiber is calculated, for the first time. The effects of the fiber parameters on the pressure sensitivity of dynamic
grating are discussed.
Optical fiber properties influence on strain coefficient Cε of Brillouin frequency shift
Show abstract
Usually, strain and temperature coefficients of Brillouin frequency shift (BFS) of optical fibers result from experimental
measurements. For the first time, theoretical strain dependence of BFS is analyzed depending on fiber properties. Based
on a FEM-2D modeling, the strain coefficient Cε is determined considering geometrical profile, doping composition and
drawing conditions. Theoretical results showed great accordance with measurements for different types of single-mode
fibers. The Cε coefficient is evaluated with a relative uncertainty better than 8%. Significant Cε magnitude variation has
been observed depending on doping profile. This paves the way towards major improvement of strain optical fiber
sensors.
Distributed fiber optic pressure sensors based on a photonic crystal
Show abstract
A distributed fiber optic pressure sensor based on a piece of the photonic crystal fiber (PCF) is proposed and
experimentally demonstrated. The sensor is fabricated by splicing the PCF with a single-mode fiber (SMF), and the free
end face of the PCF is filmed with a reflectivity of 99%. A Michelson interferometer is formed in the PCF. The pressure
position can be located by measuring the phase difference of the interferometer, and the pressure can be interrogated by
measuring the amplitude of the optical spectrum. The experimental results show that the pressure and its position along
the PCF can be simultaneously interrogated.
Study on multi-channel distributed fiber optic gas monitoring system
Show abstract
This paper presents a method using tunable diode laser spectroscopy and wavelength modulation technology to realize the
research of multi-channel distributed fiber optic gas monitoring system. The sensor probe consist of gas cell and fiber optic
without any circuit, therefore this system can realize the prediction and forewarning of gas concentration of non-electrical,
long-distant, on-line and distributed. The experiment shows four channels fiber optic gas monitoring system is not
influenced by variation of fiber length, and the system can get a correct detection of methane concentration value.
Improvement of pulse shape on Brillouin optical time domain reflectometry
Show abstract
The signal noise ratio (SNR) enhancement of spontaneous Brillouin scattering spectrum on Brilloluin optical time
domain reflectometry (BOTDR) sensing system have been demonstrated experimentally through changing the pulse
shape. With the same pulse width, the SNRs of the coherent detection power spectrum for trapezoidal pulse and
triangular pulse increase relative to that of rectangular pulse. The sensing distances are also increased. This will be
helpful to improve the spatial resolution or achieve longer sensing distance in the BOTDR sensing system.
Single-ended distributed Brillouin sensing with high spatial resolution
Show abstract
A novel single-ended distributed fiber sensor based on stimulated Brillouin scattering (SBS) with high spatial resolution
is proposed and experimentally validated. This single-ended technique is based on modulated optical long pulse that
consists of two sidebands. The probe wave is obtained by an attenuator and Fresnel reflection. The spatial resolution is
only limited by the fall-time of the long pulse without secondary "echo" phenomena. In addition, the configuration of
this single-ended technique is very simple and has no need to spend extra measurement time compared with conventional
BOTDA.
Brillouin optical time domain reflectometry using a reference Brillouin ring laser
Show abstract
A single frequency Brillouin fiber laser used as a local oscillator for Brillouin optical time domain reflectometry
(BOTDR) is designed and developed without using expensive instruments or complicated system. A BOTDR with this
reference Brillouin laser for distributed measurement over 53km sensing fiber has been experimentally demonstrated.
Experimental results show that the system can accurately measure the Brillouin scattering spectrum distribution with a
much lower frequency bandwidth detector.
Spatial resolution improvement based on intensity modulation in measurement of Brillouin dynamic grating localized by correlation domain technique
Show abstract
We demonstrated that intensity modulation synchronized with laser frequency modulation enhances the spatial resolution
in the measurement of Brillouin dynamic grating (BDG) spectrum localized by the correlation domain technique.
Following the correlation domain principle, the stimulated Brillouin scattering is localized in so-called correlation peak,
but the peak actually has side lobes which excite the BDG out of the peak region. To overcome this, we applied intensity
modulation and apodize the optical spectrum of the participating waves to suppress the side lobes. We confirmed spatial
resolution improvement from 75 cm to 17 cm in a measurement fiber of 500 m.
Verification of Brillouin optical correlation domain reflectometry by numerical simulation
Show abstract
Numerical simulation method is proposed for Brillouin optical correlation domain reflectometry in order to verify the
characteristics in strain or temperature distributed sensing. The simulation results for the Brilluion gain spectrum
obtained by the system agree well with previous theoretical analysis and experimental results, which make us understand
more this reflectometry for further performance improvements.
The use of Walsh functions in modulating pump light of high-spatial-resolution BOTDA with NRZ pulses
Show abstract
We have previously introduced phase modulation into pulsed pump of Brillouin Optical Time Domain Analysis
(BOTDA) in order to obtain high spatial resolution. In this study, we propose to use Walsh functions in coding nonreturn-
to-zero (NRZ) formatted pump pulses of the high-spatial-resolution BOTDA to increase signal-to-noise ratio
(SNR). Contrary to previous reports, it is numerically and experimentally verified that the use of the Walsh functions in
the high-spatial-resolution BOTDA allows the increase in SNR without deteriorating its spatial resolution expected. We
demonstrate measurements with 1.5 dB improvement in SNR and with approximately 0.2 m spatial resolution.
Birefringence distribution mapping in optical fibers with a coherent polarization-OTDR
Shuangshou Yang,
Xiuzhen Wei,
Chao Gao,
et al.
Show abstract
We propose a new Polarization-OTDR system to measure the distribution of birefringence. The evolution of state of
polarization(SOP) is detected utilizing the coherent Rayleigh scattering light in two fibers (Reference fiber and fiber
under test). The birefringence is calculated based on Jones matrix, and the trace of Jones matrix can describe the
magnitude of birefringence. The resolution and SNR of coherent Polarization-OTDR is significantly improved.
Photonic doppler velocimetry system based on bare fiber probe
Show abstract
It is proposed to use bare fiber bundle as probes of photonic Doppler velocimetry (PDV) system to improve the spatial
resolution of measurement. Two-point velocity measurement with spatial resolution of 375μm is experimentally realized.
Because of smaller probe spacing, the measuring results obtained from a probe would be influenced by the reflected light
from another probe. Theoretical and experimental results show that the measuring results are not affected by the stray
light when the target surface has the same velocity, and the measuring errors are related not only with the velocity
difference of two points but also with the intensities and the initial phases of the sensing and stray light when the target
surface has different velocity.
Raman-assisted DPP-BOTDA sensor employing Simplex coding with sub-meter scale spatial resolution over 93 km standard SMF
Show abstract
Differential pulse-width-pair BOTDA technique is combined with bi-directional Raman amplification and Simplex
coding to achieve sub-meter spatial resolution over very long sensing distances. Numerical simulations are used to
optimize the power levels of the Raman pumps, avoiding nonlinear effects and pump depletion. Distortions in the
Brillouin gain spectrum due to acoustic-wave pre-excitation are also avoided by numerical optimization of the pulse
width and duty cycle of return-to-zero Simplex coding, providing significant SNR enhancement. We demonstrate 50 cm
spatial resolution over 93 km of standard SMF with a strain/temperature accuracy of 34με/1.7 °C, respectively.
Simultaneous multi-point measurement of refractive index using optical fiber sensor based on an arrayed-waveguide grating
Show abstract
A simple Fresnel reflection-based optic fiber refractometer for simultaneous multi-point refractive index measurement
based on an Arrayed-Waveguide Grating (AWG) is proposed. Different channel lights divided by the AWG are marked
with different central wavelengths and their Fresnel reflective lights from the fiber-solution interfaces are used to
measure the refractive indies of the inserted different solutions at the same time. The refractive index sensitivity for each
channel sensing head reaches up to 157.1dB/RIU.
Mechanism of refractive index distribution measurement based on etched fiber Bragg grating
Show abstract
We present the mechanism of refractive index (RI) distribution measurement based on an etched fiber Bragg grating
(FBG) with a residual diameter of about 5.73 μm. The etched FBG is installed in a micro-tube where the RI of the liquid
medium decreases linearly alone its axis. Experimental results show that the sensitivity of RI gradient and the average
sensitivity of RI of this sensor is 336.2 nm·mm/RIU and 49.44 nm/RIU, respectively, when the RI ranging from 1.330 to
1.3586. The RI distribution of the inhomogeneous liquid medium can be obtained by the RI gradient sensitivity and the
average RI sensitivity.
Distributed optical fiber vibration waveform sensing system based on compensating interferometer
Show abstract
A distributed optical fiber vibration sensing system based on compensating interferometer is established and a distributed
optical fiber vibration waveform detecting technology based on a MZ compensating interferometer and compensating
interference of Rayleigh backscattering lights in adjacent areas is put forward. In laboratory experiment, the sensing fiber
is a 2500m SM fiber. By exerting 500Hz PZT vibration signals on the fiber at 40m, 430m, and 2500m, the locations of
the signals are obtained by phase demodulation. But there is a crosstalk at 40m because of multiple scatterings. The
spatial resolution is 40m and the SNR is 18dB.
Hydrogen influence on Brillouin and Rayleigh distributed temperature or strain sensors
Show abstract
Distributed optical fiber sensors are a clue technology for the monitoring of geological repository for long-lived nuclear
wastes. Environment includes hydrogen whose influence on Rayleigh and Brillouin scatterings is experimentally
evaluated. Induced propagation losses are quantified, as a function of wavelength and fiber dopants. 1310nm resulted the
most favorable working wavelength. Distance range would anyway be reduced down to a hundred meter. We show
hydrogen also induces Brillouin frequency shifts, up to 21MHz which corresponds to large temperature and strain
measuring errors if not corrected. Fluorine fibers appeared more sensitive for short hydrogen exposure than other tested
fibers.
Time division multiplexing optical time domain reflectometry by directly synthesizing heterodyne intermediate frequency
Show abstract
A time division multiplexing optical time domain reflectometry (TDM-OTDR) based on multi-frequency probe
light and directly synthesizing heterodyne intermediate frequencies (IFs) is proposed and experimentally demonstrated.
Five time division multiplexing probe frequencies are obtained by synchronous control of an arbitrary waveform
generator and a phase modulator. Experimental results achieve 6.5dB dynamic range enhancement, compared with
conventional coherent OTDR.
Investigation on threshold of stimulated Raman scattering in optical fibers
Show abstract
The evolutions of residual pump power and forward Raman Stokes scattering light power with increasing pump
power level are investigated by numerical simulation. The Stokes power variation shows obviously threshold
characteristic which is similar to that of laser diode, and the pump power corresponding to the maximum of the second
derivative of the Raman Stokes signal vs. pump power curve was defined as the pump threshold. A threshold equation
was obtained by fitting the results obtained for different fiber characteristic parameters β. Simple experiments were
carried out with a pulse pump laser and a 24 km long single mode fiber, and the experimental results agree well with the
result obtained threshold equation numerically.
Brillouin gain spectrum characteristics for temperature compensation in fiber optic distributed strain sensor
Aleksander Wosniok
Show abstract
We studied Brillouin gain spectrum characteristics in single-mode optical fibers with different refractive index profiles to
realize temperature-corrected distributed strain measurement. The measured Brillouin frequency shift (BFS) features
much stronger dependence on the longitudinal strain in the sensor fiber than on the temperature distribution along the
fiber optic sensor. By detection of slight structural changes in monitored civil structures, such as dams, pipelines and
tunnels, the influence of temperature on the measured BFS cannot be neglected.
Reflection properties of Brillouin dynamic gratings in coiled single-mode fibers
Shinya Takigawa,
Tsuneo Horiguchi
Show abstract
Brillouin dynamic gratings (BDGs) have been usually created in polarization maintaining fibers (PMFs). In this study,
we use conventional single-mode fibers (SMFs) which are coiled with care. In addition, we derive approximations of the
BDG properties based on the moving fiber Bragg grating (FBG) model. We find the experiments agree well with the
calculations in terms of fundamental BDG properties: frequency offset, reflectance, bandwidth. Our results therefore
reinforce the previous reports on the BDGs in which the agreement between calculations and experiments was not
satisfactory. Furthermore, our results suggest the possibility of locating bent fibers with high sensitivity.
Ultra-sensitivity, ultra-large dynamic all-fiber optical coherence domain polarimetry
Show abstract
An all-fiber optical coherence domain polarimetry (OCDP) is presented, which can increase the detection sensitivity and dynamic range simultaneously. An all-fiber OCDP system has been built, and the detecting sensitivity of polarization crosstalk can reach -98dB, meanwhile, the dynamic range can keep in 98dB. This method realizes the highest performance of the date OCDP technology, and provides an effective measurement and evaluation tools for high performance fiber optic devices and sensor system.
High performance phase demodulator for interferometric optical fiber sensor using novel ameliorated PGC algorithm
Show abstract
We demonstrate a high performance phase demodulator for interferometric optical fiber sensor using novel
ameliorated PGC algorithm. Theoretical and experimental results show that the novel ameliorated PGC algorithm has the
high stability of resist rapid change of light and low harmonic distortion advantages. Experiment results show that phase
demodulator has a resolution of 2×10-5 rad / √Hz, a dynamic range of 112 dB @ 50 Hz, a linearity of better than 0.9999
and a THD of below 0.1 %.
Brillouin sensing for perimetric detection: the SmartFence project
Show abstract
Security is a rising market, and solutions based on distributed sensing provide answers adapted to requests of citizens and
industrials. We developed the SMARTFENCE concept, to provide an innovative solution for enhanced perimeter
security of critical infrastructures. It includes a new kind of optical cable deployed on fences, a Brillouin instrumentation,
and a dedicated signal processing. Several 20 m-long fences were equipped with such sensing cable and tested by
commandos, then intrusion signals were used to develop the signal processing. Field trials resulted in a very sensitive
solution, thanks to an innovative deployment procedure of optical cables on fences. The project ends with a long term
demonstration: an electrical substation, 670 m perimeter, has been equipped with the fiber sensing cable, on two fence
levels. This validation provides an important experience feedback and the monitoring system validation.
Bipolar pulse coding for enhanced performance in Brillouin distributed optical fiber sensors
Show abstract
We propose and experimentally demonstrate the possibility to use a pump signal based on bipolar pulse sequences using
single-sideband suppressed-carrier (SSB-SC) modulation in Brillouin optical time-domain analysis (BOTDA) sensors.
The SSB-SC modulated pump makes a sequential use of the Brillouin gain and loss spectra, increasing the intensity
contrast of the measurements. The method is demonstrated using bipolar Golay codes along a 50 km sensing fiber and
2 m spatial resolution. Results indicate that the use of bipolar sequences provides a higher SNR enhancement and
stronger robustness to pump depletion in comparison to BOTDA systems employing conventional unipolar sequences.
Impacts of Kerr effect and fiber dispersion on long-range Brillouin optical time-domain analysis systems
Show abstract
In this paper, we theoretically and experimentally investigate the impacts of Kerr effect and fiber dispersion on longrange
Brillouin optical time-domain analysis (BOTDA) systems. The results show that the self-phase modulation (SPM,
Kerr effect) can induce considerable continuum spectral broadening on a Gaussian pump pulse at a relative low power
for both normal and anomalous dispersion fibers; with the cooperative effect of SPM and anomalous dispersion, the
modulation instability can cause discrete spectral broadening on a square pump pulse at a relative high power. The
detrimental effect of pump pulse spectral broadening could reduce the performance and sensing-range.
Continuous wavelet transform for non-stationary vibration detection with phase-OTDR
Show abstract
This paper proposed using continuous wavelet transform to analyze the non-stationary vibration in the distributed
vibration sensor based on phase optical time domain reflectometry (OTDR). The continuous wavelet transform approach
allows detection of both the frequency and time information of vibration simultaneously. Distributed vibration
measurements of 200Hz and 200 Hz to1 kHz sweep events over 20cm length have been demonstrated using the single
mode fiber.
Sweep-free Brillouin time-domain analysis (SF-BOTDA) with improved spatial resolution
Show abstract
Sweep-free Brillouin optical time domain analysis (SF-BOTDA), which uses multi pump and probe tones for a much
faster determination of the Brillouin frequency shift, has suffered from a trade-off between the required spatial resolution
and the inter-tone frequency spacing. A new implementation of the technique, involving a novel sequencing of the probe
signal with respect to the pump multi-tone pulse, together with advanced post-processing, removes this trade-off,
allowing the method to achieve spatial resolutions comparable to those of classical BOTDA without sacrificing tone
granularity. A spatial resolution of 2m is experimentally demonstrated.
Performance tests of PM optical fiber coupler based on optical coherence domain polarimetry
Show abstract
A method using all-fiber Optical Coherence Domain Polarimetry (OCDP) for polarization performance tests of PM
coupler is presented in this paper. It aims to measure distributed polarization crosstalk of different devices such as
coupler power coupling part, input fiber or output fiber. An all-fiber OCDP system has been built based on white light
interference theory, and the detecting sensitivity of polarization crosstalk and dynamic range are better than 85 dB,
meanwhile, spatial resolution reaches ±5cm. Extinction ratio, the quality of optical path connection in the 2×2 PM
coupler have been measured. The results show that all-fiber OCDP has advantages to lumped extinction ratio test. This
measurement provides an effective testing method for research and development of high-performance PM coupler and
beam splitter.
Research on coherent Rayleigh backscattering and signal processing method in phase-OTDR
Show abstract
There have been a number of papers focusing on fiber distributed sensing with coherent Rayleigh backscattering
published. However, up to now, very limited research articles on investigation of coherent Rayleigh backscattering signal
waveform and its physical mechanism have been reported. This paper first proposes a theoretical derivation to illustrate
coherent Rayleigh backscattering waveform. The theoretical model is then proved with numerical simulation and
experimental measurement. In addition, signal processing method is an important factor on the performance of a phasesensitive
OTDR system. An improvement of signal processing method, which is consisted of digital average, moving
average and interval subtraction, with good effect on locating external perturbation is also introduced.
Brillouin scattering based sensor in high gamma dose environment: design and optimization of optical fiber for long-term distributed measurement
Show abstract
Brillouin sensing is an interesting technology to monitor strain inside large civil engineering structures like nuclear waste
repository. In radiative environments, performance degradation of Brillouin systems still needs to be investigated. In this
paper, we fully characterized the Brillouin response of two different optical fibers, including the SMF28 fiber from
Corning, under high gamma doses. Radiations increase the fiber linear attenuation and can also lead to a shift in the
Brillouin frequency. We reduced these effects by designing a radiation resistant optical fiber. This fiber is well adapted
for distributed sensing application using Brillouin scattering in MGy dose level environment.
Life-cycle monitoring for RC structural prestress loss utilizing optical fiber distributed sensors
Show abstract
Prestress loss is critical to impact the safety of prestressed reinforced concrete (RC) structures. Unfortunately, up to now,
there are no qualified techniques to handle this issue. This paper proposes a life-cycle concept to monitor the full-scale
prestress loss of RC beams utilizing optical fiber distributed sensors. And the optical fiber distributed sensors-based
smart steel strands and load cell were configured. A prestressed RC beam with embedded smart steel strands was built to
illustrate the above methodology. The prestress loss data obtained from the smart steel strand and load cell agrees well,
and also matches that from the theoretical code.
A hybrid Raman/FBG sensing system for simultaneous measurement of temperature and strain
Show abstract
A hybrid Raman distributed temperature sensor (RDTS) and low-reflective fiber Bragg grating (LR-FBG) sensing
system is proposed to achieve simultaneous measurement of distributed temperature and quasi-distributed strain. In this
system, a method based on wavelength-swept optical time domain reflectometry (OTDR) is applied to interrogate the
wavelength of reflective signal from the LR-FBGs with similar resonate wavelengths arranged in serial, while RDTS is
realized by using the same light source. It is proved that such a Raman sensor and the LR-FBG sensor can be integrated
into one system without interference by experiment.
Rating the performance of a Brillouin distributed fiber sensor
Show abstract
The effect of the characteristics of a generic distributed fiber sensor based on stimulated Brillouin scattering on the
amplitude of the response is analyzed and a relation between the measurement noise on the time traces and the error on
the determination of the Brillouin frequency shift is established. This makes possible to propose a simple figure-of-merit
to fairly compare the performance of Brillouin distributed sensing systems.
Reducing location error and processing time of dual Mach-Zehnder interferometric fiber perturbation sensor using zero-crossing analysis
Show abstract
A novel location algorithm based on zero-crossing analysis is introduced in this paper to reduce the location error and
processing time of dual Mach-Zehnder interferometric (DMZI) fiber perturbation sensor. The algorithm can extract highfrequency
part from original signal and obtain perturbation location using cross correlation in a very short process time.
By extracting high-frequency signal, the algorithm can also acquire a low perturbation location error. Experiment results
show that the perturbation location error only has 10 m and the processing time is less than 0.13s in the case of 10MHz
sample rate.
Continuous online partial discharge monitoring system
Show abstract
In this paper, we propose and demonstrate a new type of fiber optic sensor system for remote continuous monitoring and
detection of partial discharge (PD) from power equipment. The sensing system uses an antenna which is connected to a
vertical-cavity surface-emitting laser (VCSEL). The modulated light by the PD signal is transmitted through an optical
fiber and measured remotely by an optical receiver. Laboratory experiments have shown that EMOptic sensor has high
sensitivity and signal to noise ratio by comparing Electromagnetic (EM) sensor and other sensors. It provides a feasible
remote PD monitoring technique for power equipments. A completed prototype sensing system based on this technique has
been installed in a commercial building for field trial. The system can be accessed via internet anytime and anywhere.
Desensitized encapsulation FBG sensor for smart cable in bridge
Show abstract
The proposed desensitized encapsulation structure solved the problem that more than 5500με test range for FBG sensor.
The single steel wire with proposed FBG sensor tension test in laboratory before and after fatigue experiment showed the
rationality and reliability of sensor structure. A scheme using desensitized encapsulation FBG sensor to fabricate smart
cable which was compatible with production process of parallel steel wires cable was designed. The specimen cable
tension test verified sensors high survival rate of the design scheme and good long-term precision after fatigue
experiment. Also the actual application of smart cable was tested by one bridge during the construction and operation
stage.
Carbon-coated fiber Fabry-Perot sensor for harsh environments
Show abstract
Carbon coatings on optical sensors can protect them from being corroded by H2 and H2O. In this paper, a laserinduced
chemical vapor deposition device is presented to grow carbon films on the fiber Fabry-Perot sensor. The
scanning electron microscopy and Raman spectroscopy are used to analyze hermetic properties of the carbon coating.
Experimental results demonstrated that the carbon-coated sensor exhibited a good long-term stability in a 72MPa and
300°C environment. The fluctuation of the cavity length is only 1nm during seven months after a short-term decrease.
On-line load monitoring of a tufting needle using optical fibre Bragg grating sensors
Edmon Chehura,
Giuseppe Dell'Anno,
Tristan Huet,
et al.
Show abstract
Optical fibre Bragg grating strain sensors are used to monitor the dynamic loads experienced by a tufting needle installed
on a commercial robot-controlled tufting tool during the tufting of a dry carbon fibre preform. The influence of the
thread and thickness of the preform lay-up were investigated. Maximum axial compression strains of ~-250 με, and
bending strains of 1100 με were measured during the tufting of a 4 ply quasi-isotropic carbon fibre dry preform.
Mechanical strength of silica fiber splices after exposure to extreme temperatures
Marcus Perry,
Pawel Niewczas,
Michael Johnston,
et al.
Show abstract
By using a combination of type-I and regenerated gratings, the mechanical strength of optical fiber splices after exposure
to temperatures over 1300 °C was characterized. Splice strength was found to decrease with temperature with a secondorder
polynomial dependence after exposure to environments hotter than 500 °C. Splices exposed to temperatures above
1300 °C were 80% more fragile than non-exposed splices. The lack of optical attenuation and the narrowing distribution
of breaking strengths for higher temperatures suggest surface damage mechanisms, such as hydrolysis, play a key role in
weakening post-heating and that damage mechanisms dominate over strengthening induced by crack melting.
A new-type non-contact FBG vibration detecting sensor for rotating machinery
Show abstract
Currently, the vibration measurement and monitoring of the rotating machines has become the primary means of fault
diagnosis. This paper proposed to develop a magnetic coupling non-contact machinery vibration detection sensor based
on fiber Bragg grating (FBG). The magnetic coupling technology and elastic diaphragm are adopted to achieve the
vibration detection by changing the axial strain of optical fiber. Theoretical analysis and static experiment show that the
function of output wavelength and the measured spacing is exponential decrease. Dynamic vibration measurement shows
that the proposed FBG diaphragm accelerometer provides a wide frequency response range (0-90Hz), identifying it as a
good candidate for machinery health monitoring.
High-accuracy optical pressure sensor for gas turbine monitoring
Fabrice F. M. Maillaud,
Ralf D. Pechstedt
Show abstract
In this paper, we present an improved optical pressure sensor system for harsh environments. By introducing temperature
measurement and compensation, we were able to improve the dynamic pressure performance of the sensor and also
provide accurate static pressure and temperature measurements.
An optical fiber F-P acoustic emission sensor system for the detection of steel crack initiation
Show abstract
In this paper, an optical fiber Fabry-Perot(F-P) acoustic emission(AE) sensor system for the detection of steel crack
initiation has been investigated. The F-P sensors were fabricated by using quartz diaphragm, glass tube and fiber optic.
And the signal processing circuit was designed by using an intensity demodulation method. The test of steel crack
initiation was simulated by using a pencil lead break experiment. The results indicate that the F-P sensing system can
detect weak AE signals at the frequency between 20 kHz and 1MHz, which could be used to on-line monitor of the steel
structure health.
Model analysis of single-mode optical fiber extrinsic Fabry-Perot interferometric sensors
Show abstract
We revise the demodulation model for single-mode optical fiber extrinsic Fabry-Perot interferometric sensors on
account of mode-coupling theory and manufacturing imperfections of fiber sensors. This new model can be used to
estimate the large system errors of absolute measurements and explain the big difference of demodulation results with
different incident central wavelengths of light source. The measurement error of traditional free-space plane-wave
model in demodulating cavity-length variation of fiber sensors is also analyzed.
Pipeline auto-mapping system based on inertial technology
Shuang Gao,
Xianmu Li,
Tie Lin
Show abstract
The precise trajectories of long gas and oil pipelines surveying is a key part of pipeline integrity management (PIM)
system. This paper presents a pipeline auto-mapping system based on inertial technology. The system includes an inertial
measurement unit (IMU) as the core component, odometers and a set of cartographic landmarks as the auxiliary signals.
A post-processing off-line computer system receives downloaded inertial measurement, odometer, and landmarks data
and though the use of Kalman filters to estimate the system state. On simulation experiments, the accuracy of integrated
navigation system is approximately 0.1m per Km.
Phase noise characteristics for four-wave transmission in a long-haul interferometric fiber sensing system
Show abstract
Phase noise characteristics for four-wave transmission in a long-haul interferometric fiber sensing system are
investigated. It is found that the phase noise in the presence and absence of four-wave mixing (FWM) is almost the same,
which indicates that the influence of FWM can be negligible. It is due to that the bandwidth of the photodetector used in
the fiber sensing system is often narrower than the beat frequency between FWM induced light and signal light, leading
the beat noise to be filtered. This noise characteristic is different from that in the fiber communication system and
provides guidance for the practical application of the interferometric fiber sensing system.
Depolarizer improvement for optical fiber vibration sensor
Toshiki Kubo,
Ataru Takahashi,
Nancy Zhao,
et al.
Show abstract
An optical signal with a polarization dependence behaves as a noise signal in a vibration sensing optical fiber. To
remove the noise signal, the optical fiber vibration sensor needs to have a depolarizer. Fusion splicing the polarization
maintaining fiber with a 45 degree angle offset is a common method to produce the depolarizer.
In this paper, we present a method to improve the depolarizer for the vibration sensor through the use of fusion splicing.
We succeeded to reduce the noise with the improved depolarizer that uses a method to observe the fiber end surface of
polarization maintaining fiber for analyzing the polarization plane.
Research of laser induced breakdown spectroscopy for detection of trace Cd in polluted soil
Shiqing Chen,
Xiaohong Ma,
Huafeng Zhao,
et al.
Show abstract
In this article, the quantitative analysis of trace Cd in polluted soil has investigated with Laser Induced Breakdown
Spectroscopy (LIBS) technique by calibration. In order to improve its detection sensitivity and limit of detection (LOD),
a spectral data processing approach, Radial Basis Function (RBF) neural network and Lorentz function were introduced
to optimize the LIBS spectral data, was used and verified in this article. The calibration curve of Cd in soil was obtained,
its linear correlation is 0.9998, and the LOD of Cd in soil is 16.5 mg/kg, in this article.
Condition monitoring of reciprocating compressor using FBG-based sensors in petrochemical industry
Show abstract
Real-time, on-line measurement of key physical parameters as well as their variations is the most crucial problem for
safety running of reciprocating compressors in petrochemical plants. In this paper, a method for condition monitoring
and fault diagnosis of reciprocating compressor based on FBG sensors is proposed. A fiber optic accelerometer is
demonstrated, which is used for detecting the vibration of crankcase, crosshead and cylinder of the compressor. FBGbased
temperature sensors are used to monitor the variation of the suction/vent valve temperature. A monitoring system
included hardware and software for the reciprocating compressors is developed and applied in a petrochemical plant.
A common path fibre optic based interferometric displacement sensor with enhanced range
Show abstract
The transfer functions of single and dual interferometric cavities were measured with 1300nm high power,
tuneable fibre laser with a coherence length of 20mm. The interferrogram of the dual cavity is complex. The
positions of the surfaces in the cavities were determined using Fast Fourier transforms. A feature of the dual
cavity is an increase in the 'effective' coherence length of the source, illuminating a simple common path
interferometer. A 4*1 optical switch was incorporated with the laser allowing near simultaneous data to be
recorded from up to 4 probes. A potential application for a dual cavity probe is discussed.
Rail corrugation measurement using fiber laser accelerometers
Show abstract
This paper presents a rail corrugation measurement system based on fiber laser accelerometers (FLAs) which are
installed on the bogie of the train. When the train passes the rail with corrugation, the corrugation induced acceleration of
the bogie will be detected by the FLAs. An inertial algorithm based on double integration and wavelet denoising method
is proposed to accurately estimate the rail corrugation. Field test is carried out on the Datong-Qinhuangdao Railway in
north China. The test results are compared with the results of a rail inspection car, which shows that the fiber laser
sensing system have a good performance in rail corrugation monitoring.
Effect of temperature on methane gas concentration by tunable diode laser absorption spectroscopy
Yanjie Zhao,
Yanfang Li,
Tingting Zhang,
et al.
Show abstract
The effect of temperature on gas absorption characteristics is obvious. When the tunable diode laser absorption
spectroscopy (TDLAS) technique is applied to monitor the methane gas concentration, the influence of temperature must
be correction in order to measure the gas concentration accurately. Based on HITRAN database, the absorption
characteristics of methane near infrared spectrum with temperature have been researched. Then a multiplexed fiber optic
methane monitoring system is designed and the distributed feedback (DFB) laser is employed as laser source. The effect
of the temperature on the system is emphasized. The results show that it obviously improved concentration precision by
compensating retrieval concentration. It is valuable references for the gas detection in practical applications.
The rail bridge bearing monitoring system base on FBG
Show abstract
Based on optical fiber grating sensing technology,the bridge bearing displacement was monitored for a long term
online.The sensor performance and its installation method were analyzed.The structure of the monitoring system was
studied,the data acquisition system was realized.The 3G network which transfered the data remotely and data storage
method were discussed to build a remote data center. The composition of the database was proposed, and the relation
between the displacement and the temperature for the bridge bearing was discussed on the historical data.The basis on
the bridge safety monitoring was provided.
A hetero-core spliced fiber optic SPR sensor network for extensive-area natural environment monitoring
Show abstract
This study discusses the development of a simple and cost-effective natural environment monitoring system constructed
using a hetero-core spliced fiber optic SPR sensor by which simultaneous data communications and sensing functions
can be achieved on the same line. In order to verify the data communication and sensing function of sensor in an
extensive-area of 2000 meters, laboratory experiments employ a SPR sensor with 50-3-50μm core type hetero-core
structure which is coated with gold (Au) at 25nm and tantalum pentoxide (Ta2O5) at 60nm. The proposed system has
been developed such that the data communication and sensing function are successfully demonstrated.
Diffuse-light absorption spectroscopy for discriminating Belgian beers
Show abstract
This paper presents an optical method for authenticating Belgian beers. A set of 86 beers is considered, 50 of which were
produced in Belgium, while the others worldwide. A fiber optic setup for diffuse-light absorption spectroscopy was used
to achieve a turbidity-free spectroscopic information in the visible and near-infrared bands. In addition, turbidity and
refractive index measurements, measured by means of conventional hand-held instrumentation, were added for
completing the optical characterization. The entire optical data set was processed by means of multivariate analysis to
achieve the discrimination of Belgian beers with respect to all the others.
Experimental qualification and validation of fibre optic strain sensors
Constanze Schilder,
Nadine Kusche,
Vivien G. Schukar,
et al.
Show abstract
Strain sensors used in practical applications must provide reliable measurement data. To achieve this, sensor systems
must be validated by using experimental facilities that enable physically independent statements about the performance
of the sensor components. The paper describes qualification and validation procedures using a special facility to qualify
surface-applied strain sensors and to achieve reliable sensor results. Based on examples concerning fibre optic strain
sensor patches with and without FBG sensors, the determination of the strain gauge factor also under combined thermal
and mechanical loading will be presented. These results are the basis for development of guidelines and standards.
Displacement monitor with FBG deforming ring and its application in high speed railway
Show abstract
A displacement monitor with deforming ring is developed to ensure the FBG suspended and to avoid it to be chirped by
covering glue. The mechanical analysis provides ring size to ensure suitable BFG wavelength shift extent within detected
range. Two pieces of FBG are crosswise fixed on the ring and pre-drawn properly. Rail creep force of high speed railway
makes one tense, the other compress. To add these two wavelength shifts, the sensitivity is doubled, and environmental
temperature interference is eliminated. Its general error is ±0.25% FS; repeatability is 0.2% FS; resolution is 0.1mm; the
temperature error, from -20 to 60Cº, is ±0.45mm in 50mm range.
The bridge heavy vehicle identification system based on optical fiber sensing technology
Show abstract
In order to meet the research of bridge health and safety monitoring system, and provide heavy vehicle load
spectrum for the research, the heavy vehicle classification identification system was designed based on high-speed FBG
demodulation system and FBG sensing test technology according to the structure characteristics of the large span
orthotropic steel box girder cable-stayed bridge. The heavy truck load cases were designed for the loading test, and
heavy vehicle classification standard was provided of the identification system according to the loading test.
Structural health monitoring of reinforced concrete beams by means of embedded fiber Bragg grating sensors
Show abstract
This study aims to investigate the mechanical behavior of FRCM composite-strengthened concrete beams using
embedded FBG sensors. FBG sensors were installed both on the tensioned surface of the concrete beam and on the PBO
mesh woven, that had been applied using cementitious mortar without any epoxy resin. Conventional strain gauges were
used to compare results measured from the FBG sensors. Under three-point bending, a marked difference between strains
measured in the concrete and those gotten on the reinforcement net was observed. A theoretical model is presented to
explain the observed discrepancy.
Field test of an eight-element fiber laser hydrophone array
Show abstract
In this paper we repot the field test of an eight-element fiber laser hydrophone (FLH) array. The design of the fiber laser
hydrophone, the schematic of the array, the WDM based interrogator system, and the field test results are given. The
field test results show that the eight-element FLH array have equivalent performance as piezoelectric hydrophone array.
Optical fiber sensing technology application in long span highway-railway cable-stayed bridge
Show abstract
The long span highway-railway cable-stayed bridge bears huge permanent load and heavy moving load. The structural
internal force is the key for bridge safety operation. This paper introduces the fiber Bragg grating (FBG) strain sensor,
FBG force-testing ring and FBG acceleration sensor to monitor the pivotal parameters of dynamic strain, cable force and
dynamic characteristics. The bridge health monitoring system based on the three FBG sensors has been applied in
Tianxingzhou bridge. The FBG sensors were monitoring during bridge construction stage, load test and normal
operation. The analysis based on engineering monitoring data indicates that the data of FBG sensors are stable and
reliable.
Continuous pressure and temperature monitoring in fast rotating paper machine rolls using optical FBG sensor technology
Show abstract
A fiber optic Bragg grating (FBG) sensor and interrogation scheme has been designed to capture the
momentary peak pressure forces in the nip of two adjacent paper machine rolls. The spatial distribution of
these nip forces along circumference and length of the roll, for production speeds of up to 2000 m/min are
investigated. Additionally, this FBG sensor system measures the temperature distribution in the roll cover.
FBG sensor embedding has been optimized for the implementation of pressure force measurements in
various roll cover materials. High strength draw tower grating (DTG) sensor arrays were used for the
embedding process combined with spectrometric interrogation and autonomous power supply technologies.
This results in an extremely robust fiber optic sensor system for operation at rotation speeds of 700 rpm,
equivalent to centrifugal accelerations of 300 G. These measurements enable immediate quality control
during various stages of the high-speed paper production process.
A four-element optical fiber 4C vector hydrophone array
Show abstract
A horizontal line array of four component (4C) optical fiber vector hydrophones (OFVHs) has been developed for
underwater ambient noise measurement and direction-of-arrival (DOA) estimation of underwater target. The OFVH
array consists of four OFVHs spaced uniformly over a 3 meter horizontal aperture, and each OFVH package having its
own compass. The noise floor of the OFVH array achieves -100 dB/Hz1/2 at 1000 Hz. The OFVH is composed of a threecomponent
optical fiber accelerometer with the phase sensitivities of three axes about -155 dB re rad/μPa at 1000 Hz and
an optical fiber hydrophone with the phase sensitivity -144.3 dB re rad/μPa over the frequency range from 20 Hz to 2000
Hz. A sea trial of the OFVH array has been successfully carried out in South China Sea. The trial results show that the
OFVH array can remove the 180° ambiguity in the DOA estimation by using the information of particle velocity of the
sound, and the DOA estimation accuracy obviously excelled the single OFVH and optical fiber hydrophone array. The
excellent performance of the OFVH array for use in target passive DOA estimation and tracking is proved by results.
Smart material using fiber Bragg grating transducers and shape memory alloy actuators
Show abstract
A structure based on a smart material and a PID control loop is presented in this paper. A glass fiber
reinforced plastic material is instrumented with Fiber Bragg Gratings (FBG) and Shape Memory Alloy
(SMA) actuators. The smart material and the smart structure are both successfully checked by being
subjected to different operational conditions at the laboratory. Very good responses are obtained under
both slow and quicker varying conditions.
Floating OE sensor array for offshore marine oil spill monitoring and pollution control
H. L. Cui,
David Li,
Thomas Koscica,
et al.
Show abstract
Based on our successful technology of conductance liquid level sensor, combined with the long-period fiber Bragg
grating sensor technology, a floating optical-electrical (OE) sensor array system is designed aimed at the early
monitoring of oil contamination of offshore marine oil spill and pollution control as well as the safety at sea.
Validation of an induction motor thermal model by using fiber Bragg grating temperature sensors
Show abstract
A thermal model of a three-phase induction motor is validated by using fiber Bragg grating (FBG) temperature sensors. In the experimental setup, temperature, electrical and mechanical measurements were simultaneously obtained. Eight multiplexed FBG temperature sensors in a quasi-distributed configuration were used. Results from the simulation of the
model presented a maximum difference of 0.75oC between the experimental values measured during the transient response of the motor and the simulated ones, while the steady state response converged to the measured experimental values. The
instrumentation setup allowed the inclusion of the mechanical losses in the proposed thermal model, and this is the main contribution provided by this work.
Phase locked loop based topography measurement of ultraprecision machined surface using the ball lensed and tapered fiber
ChaBum Lee,
Jin-Ho Kang,
Jae-Young Joo,
et al.
Show abstract
This paper presents the phase locked loop-based metrology concept using the lensed fibers for on-machine surface
topography measurement. The shape of a single mode fiber at the endface was designed using an ABCD matrix method
and two designed lensed fibers, ball type and tapered type, were fabricated and its performance was evaluated,
respectively. In order to achieve the on-machine measurement of the surface tophography with a high resolution, each
fiber was characterized under the following conditions; small beam spot size, long working distance and high coupling
efficiency. A piece of coreless silica fiber was spliced to a single mode fiber and a micro-sized lens or tapered shape on
coreless fiber endface was formed for the ball lensed fiber. As a result, the interferometric fringe was not found in the
case of the ball lensed fiber, but the ultraprecision machined Cu surface could be measured by autofocusing and intensity
methods. Two results were well agreed. On the other hand, very clear Fizeau interferometric fringe was observed in the
case of the tapered lensed fiber. Its performance was compared with the results of the capacitance sensor and a
commercially available white-light interferometer. Two results were well agreed. As a result, it was confirmed that the
PLL based surface profile measurement using the tapered and ball lensed fibers can be applied for on-machine surface
topography measurement.
Earthquake monitoring using fiber laser borehole seismometer
Show abstract
In this paper we report the earthquake monitoring using a fiber laser borehole seismometer. A fiber laser based
accelerometer is used in the seismometer to detect the earthquake induced acceleration. Due to the ultra-narrow line
width of the fiber laser (up to several kHz), an equivalent noise level of 50 ng can be achieved when using a fiber optic
interferometric method. The fiber laser borehole seismometer is installed in a 400 m depth hole in Yunnan Province. A
micro-earthquake (M=1.2) in Puer area is detected.
The influence of parameters measurement error on demodulation performance of PGC arctangent algorithm in optical fiber hydrophone
Kai Wang,
Qingping Shi,
Zhiguang Dai,
et al.
Show abstract
The phase generated carrier (PGC) arctangent algorithm needs to be compensated when the carrier modulation depth C
deviates from 2.63 rad. Parameters measurement error can induce an incomplete compensation in the arctangent
algorithm. The demodulation distortion due to parameters estimation error is analyzed quantitatively in this paper. The
relative amplitude error (RAE) and harmonic suppression ratio (HSR) are considered, which indicate a linear distortion
and a nonlinear one separately. Theoretical analysis shows that the fluctuation range of RAE has a linear relation with an
absolute value of δC which is the estimation error of the modulation depth C. The fluctuation range of RAE also has a
square relation with δφ1, δφ2 which are the estimation error of the phase delay Δφ1Δφ2 of fundamental and second
harmonic carriers respectively. Similarly, minimum HSR decreases by 6dB along with a doubled absolute value of δC
and by 12dB with that of δφ1. Experimental results are presented to corroborate the theory.
Test and calibration of Bragg grating based vibration sensors
Show abstract
Characterisation of fibre optic vibration sensors represents a challenge since they are not compatible with conventional
data acquisition platforms. The situation is complicated by the difficulty of applying a well described input signal, e.g. in
form of a precisely controlled acceleration level over a range of frequencies. For this, we have configured a system based
on a precision vibration exciter driven by a vibration controller. Such a system is able to reproduce the sensitivity and
frequency response of Bragg grating based accelerometers to a precision within a few percent.
Web-based refractive index monitoring system, employing LPG-FBG hybrid optical sensors
Show abstract
A new approach to refractive index sensing for biological solutions has been investigated for a web-based monitoring
system. The system was implemented such that the refractive index was monitored by an LPG-FBG hybrid sensor. The
point was how the enhanced sensitivity range of LPG could be used. For the purpose, equations were newly derived,
based on a nonlinear relationship between values of the refractive index and the resonant wavelength. The values
calculated by the equations were in good agreement with experimental values monitored by the system, enabling the
system to use the enhanced sensitivity range.
All fibre-optic simultaneous detection of optical and acoustic emission from partial discharges in silicone elastomer
Philipp Rohwetter,
Tobias Kielau,
Chaiyaporn Lothongkam,
et al.
Show abstract
In high-voltage facilities of power stations and transmission networks, discharge activities leading to catastrophic failure
can occur. Early detection of partial discharges (PD) in polymeric insulations of HV cable terminations and joints is
therefore increasingly important. This paper describes a monitoring methodology to detect PD activity in silicone
elastomer by two independent fibre-optic sensor types. Fluorescent fibre-based sensors are sensitive to plasma optical
emission already at the onset of PD while an acoustic fibre-optic sensor responds to acoustic emission from the PD
during its progression. The sensitivities of both sensor types are compared, and it is demonstrated that they provide
complementary information for fibre-optic sensor-based monitoring of high-voltage cable accessories.
Field calibration device for Raman backscatter based fiber optic distributed temperature system (DTS) technology
J. Bertrand,
Ronan Morice,
Olivier Beaumont,
et al.
Show abstract
Application of Raman DTS to nuclear structure monitoring requires good knowledge of the metrological
performance of this new technology. Periodical checks of the temperature readings will also be required on site,
in zones that will no longer be accessible after installation. A novel, in-situ thermal cartridge was developed in
order to calibrate and periodically check such measuring systems. This paper presents this innovative device and
discusses the DTS-unit performance claimed by manufacturers.
Resolution enhancement in Brillouin optical correlation domain analysis by differential lock-in detection
Show abstract
We newly propose and experimentally demonstrate a differential lock-in detection scheme for the enhancement of
Brillouin optical correlation domain analysis (BOCDA), where additional phase modulation is applied to the Brillouin
pump wave and the on-off control on which is used for data acquisition. The theoretical model and the experimental
results show that at least three-fold improvement is obtained in the spatial resolution of the distributed measurements and
the Brillouin gain spectrum (BGS) with much narrower 3dB bandwidth than that of conventional BOCDA systems is
acquired by the differential lock-in detection.
Optical monitoring of curing process of concrete with plastic optical fibers
Show abstract
In this paper we propose an optical monitoring scheme for the concrete curing process, based on plastic optical fibers.
The proposed sensor intend to use the scattering properties of the light on a plastic optical fiber, enhanced by the use of
grooves, to monitor the water content in the cement paste, and therefore to be used in the control of the cure process. The
sensor can be used in field to monitor the concrete curing process and as a result optimize the construction phase.
Towards the simultaneous monitoring of load and damage in aircraft structures using fiber Bragg grating sensors
Show abstract
Load monitoring and damage detection are the two critical aspects of aircraft structural health monitoring (SHM). The
load monitoring is achieved by detecting the local strain changes while the damage detection is generally accomplished
by the monitoring of acoustic signal changes. It would be ideal that a single sensor can perform both tasks
simultaneously. This paper reports the demonstration of using fiber Bragg gratings to monitor load and acoustic signal
applied on a simulated aircraft structure. The results clearly show that a single fiber Bragg grating sensor with short
grating length has the potential to perform both tasks simultaneously.
Investigation on upper limit of dynamic range of fiber optic interferometric sensors base on the digital heterodyne demodulation scheme
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The upper limit of dynamic range (ULDR) of the fiber optic interferometric sensors (FOIS) based on the digital
heterodyne demodulation scheme is investigated in this paper. According to the analysis of the demodulation process, the
ULDR is restricted by two factors: the heterodyne frequency and the digital orthogonal demodulation algorithm. We
discuss the influence of both the factors on the ULDR respectively in detail and give the total ULDR of the FOIS system.
Experiments with the different delayed heterodyne scheme are conducted to verify the theoretical analysis and the results
are consistent with the analysis conclusion.
A hybrid fiber-optic sensor system for multi-stress monitoring of high-voltage power transformer
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For condition monitoring of high-voltage power transformers, a fiber-optic multi-stress sensing system is suggested by combining fiber grating sensors and mandrel sensors embedded in a fiber-optic Sagnac interferometer. The gratings and the mandrel sensors measure the temperature and the vibrations at multi-locations in a power transformer. To separate and demodulate the sensor outputs, we used a wavelength-sweeping laser source and placed a fiber-optic attenuator in the Sagnac loop, which enabled to separate the Bragg wavelengths from the transmission spectrum. The temperature and vibrations of multi-locations could be measured at the same time by using optical circuit and single signal processing unit.
Analysis of fiber optic sensor application to precursory acoustic signals detection in rockfall events
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Two fiber optic sensors (FOSs) for detection of precursory acoustic emissions in rockfall events are proposed and
experimentally characterized. While both sensors are interferometric, the first one use a fiber coil as sensing element,
whereas the second sensor exploits a micro-machined cantilever carved on the top of a ferrule. Preliminary
experimental comparison with standard piezo-electric transducers shows the viability of such FOSs for acoustic
emission monitoring in rock masses.
A novel self-healing optical fiber sensor network
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To solve the survivability of sensing network for life-cycle structural health monitoring, this paper proposes a novel selfhealing
optical fiber sensor network. The self-healing network with link node or emergency component was constructed
and demonstrated by the strain measurement for a three-point bend beam with fiber reinforced polymer-optical fiber
(FRP-OF) sensors and bare optical fiber (OF) sensors. The results show that the stress state of the RC beam can be
successively detected, even some sensors fail or sensing line is broken by using the self-healing sensing network.
A novel noise suppression method for white light extrinsic Fabry-Perot interferometric fiber-optic pressure sensor in heavy oil thermal recovery downhole environment
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A novel noise suppression method is proposed for the pressure surveillance of heavy oil thermal recovery well using
white light extrinsic Fabry-Perot interferometric (EFPI) fiber-optic sensor. The moving grey model GM(1, 1) algorithm
is applied to suppress the non-stationary noise and disturbance in downhole environment. Both theoretical analysis and
field test results show that there exists a threshold effect for the moving window length selection, the optimized value of
window length occurs at the threshold point which best removes the high frequency disturbance as well as retaining the
fast change of actual pressure signal. Field test results show that the proposed method can increase the signal to noise
ratio (SNR) of pressure profile with 10.4dB, and then can effectively suppress the large deviation in the forecasting result
of daily oil production by combining temperature information.
Condition monitoring of wind turbine blades with FBG sensors
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A fiber grating sensor system for use in condition monitoring of wind turbine blades is constructed. A rotary optical
joint was used to connect the fiber grating sensors to the non-rotating signal processing unit with moderate insertion loss.
The Bragg wavelengths were interrogated by a spectrometer demodulator which consisted of a volume phase grating and
a 512-pixel photo-detector array. Using the constructed sensor system, various strain/temperature measuring experiments
have been performed. We applied fiber grating sensors at different locations on the wind turbine blade. Different types of
strain, stroke, and temperature variations were applied to the sensors and the results were analyzed according to the
sensor locations and the blade's rotary speed.
Scintillating optical fibre sensor for radiotherapy dosimetry
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An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material
coated optical fibre, which emits visible light when exposed to low level ionising radiation. The incident level of ionising
radiation can be determined by analysing the observed emission spectra. The work presented reports on the design of the
sensor and the stability of the sensor during measurement of incident x-ray energy. Initial testing of the sensor at the
radiotherapy facility at the Galway Private Clinic is presented, demonstrating the suitability of such a sensor for a range
of radiotherapy dosimetry applications.
Field trials of fiber Bragg grating settlement sensors in high-speed railways
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Novel fiber Bragg gratings (FBG) based settlement sensors are developed and the sensing performance is evaluated in
both the lab and field environments. The settlement is determined by precisely measuring the pressure of the water level
difference. The experimental results indicated that the sensor has good linearity, good repeatability and high accuracy in
the settlement measurements. The influence of temperature fluctuations on the sensor's performance is eliminated and
long-term test results proved the good stability of better than ±0.1% of the sensor. Such a FBG sensing system has been
applied to monitor the settlement of high-speed railways in practice.
Comparison of strain sensitivities of free and attached FBG strain sensors
Show abstract
The strain sensitivity of FBG-based strain sensors that had been inscribed into three different types of optical fibers were
determined for both conditions, for fibers that were glued on a specimen and for free, bare fibers, i. e. fibers that were not
bonded to a structure at the location of the FBG. The influence of the gluing technique on the strain sensitivities of the
FBG sensor elements was investigated by comparing the strain sensitivities of a multitude of attached and free sensor
elements on a statistical basis. A good agreement between the strain sensitivities of free and attached fibers was
achieved, which shows the high quality of the gluing method employed.
Study of all-fiber optic anemometer and wind direction sensor
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An all-fiber wind anemometer and direction sensor is described in this paper. The wind anemometer probe is designed as
an encoder structure while the wind direction probe is designed as a fabry-perot cavity structure, which cavity length is
changed with the wind directions. This sensor can monitor wind velocity and directions more exactly and remotely. The
method has a good reproducibility, dispense with power supply, remote measuring and anti-electromagnetic interference.
Post-Deadline Manuscripts
Brillouin optical time-domain analysis over a 240 km-long fiber loop with no repeater
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In this paper we combine the use of optical pulse coding and seeded second-order Raman amplification to extend the sensing distance of Brillouin optical time-domain analysis (BOTDA) sensors. Using 255-bit Simplex coding, the power levels of the Raman pumps and the Brillouin pump and probe signals were adjusted in order to extend the real physical sensing distance of a BOTDA sensor up to 120 km away from the sensor interrogation unit, employing a 240-km long loop of standard single-mode fiber (SSMF) with no repeater. To the best of our knowledge, this is the first time that distributed measurements are carried out over such a long distance with no active device inserted into the entire sensing loop, constituting a considerable breakthrough in the field.
Helium and regeneration in optical fibres
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We demonstrate the successful regeneration of optical fibre Bragg gratings that have been pressurized with helium instead of hydrogen. Helium-loading is performed after the inscription of the type-I seed grating. This work is of profound importance to the field of regeneration, confirming the existing theoretical model in which hydrogen plays a purely mechanical role in the regeneration process with no chemical reactions involved.
Distributed birefringence, strain and temperature measurement by homodyne BOTDR
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A novel distributed fiber birefringence, strain and temperature measurement based on homodyne Brillouin optical time domain reflectometry (BOTDR) is proposed. Birefringence measurement is based on the beat period detection of Brillouin beat of the same acoustic mode. Strain and temperature are obtained by measuring the power changes of Brillouin beat spectrum (BBS), which corresponds to the optical interaction of different acoustic modes in a complex profile fiber. The birefringence of a 4.3 km large-effective-area fiber (LEAF) was measured with 0.6-m spatial resolution, and strain and temperature at the end of a 4.5 km LEAF were measured at 1.5-m resolution in 140s.
Stimulated Brillouin scattering induced refractive index changes measurement in an optical fiber
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The refractive index changes induced by stimulated Brillouin scattering in an optical fiber are measured experimentally by polarization-decoupled four-wave mixing. Under undepleted pump approximation, net phase-matching condition depends on pump power and frequency detuning from Brillouin frequency. By investigating this net phase-matching condition, one can measure spectral change in the refractive index which is responsible for the slow light effect based on stimulated Brillouin scattering. Due to the high sensitivity of the measurement, very small refractive index changes (on the order of 10-8) versus frequency detuning can be determined experimentally, which is the lowest index change reported so far.
Graphene-based microfiber gas sensor
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In this paper, a novel graphene-based microfiber sensor is proposed and demonstrated for detection of gas concentration for the first time. As the complex refractive index (CRI) of graphene can be modulated by gas molecules in the surrounding environment, the propagating light along the graphene layer coupled by the microfiber would be altered to induce the attenuation of polarization mode intensity. Based on such a unique TE-polarization mode attenuation feature of graphene, experimental results showed that the acetone concentration can be measured accurately and quickly. Such an approach could open a window for realization of a variety of highly sensitive and fast gas or liquid sensors based on graphene, for wide applications in biological, medical and chemical fields.
Measurement of Brillouin frequency shift distribution in PLC by Brillouin optical correlation domain analysis
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We have measured Brillouin frequency shift distribution in a planar lightwave circuit (PLC) by Brillouin optical correlation domain analysis (BOCDA). We have made an experimental system specialized for the measurement of PLC, realizing spatial resolution of 5.9mm with standard deviation of 0.34MHz in Brillouin frequency shift (BFS) measurement. From the data obtained in the experiments, we have found that the BFS distribution shape along the waveguide corresponds to its route pattern in the PLC.
Ultra-small microfiber Bragg grating force sensor with greater sensitivity
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We experimentally demonstrate a compact microfiber Bragg grating (MFBG) force sensor that offers greater sensitivity under load. The FBG is fabricated by focused ion beam (FIB) milling a microfiber tapered from nonphotosensitive standard single-mode fiber. It is only ~58μm in length. The force sensitivity of the MFBG is as high as ~4133nm/N around the resonant wavelength of 1550nm, which is three orders of magnitude larger than that recorded in FBGs inscribed in untapered fibers.