Biosensors based on the plasmonic properties of Au microhole arrays
Author(s):
Ludovic S. Live;
Julien Breault-Turcot;
Olivier Bolduc;
Jean-Francois Masson
Show Abstract
The plasmonic properties of metallic nanoparticles and macroscopic Au film have been thoroughly investigated for
the development of biosensors based on surface plasmon resonance (SPR). Nanoparticle based localized surface
plasmon resonance (LSPR) is a technique extremely sensitive to molecular adsorbate, whilst conventional SPR
based on the Kretschmann configuration (macroscopic smooth Au film) is especially sensitive to bulk refractive
index. SPR currently provides the best RI resolution, a measure typically used for comparison of the potential of
plasmonic sensor. A technique that could combine high bulk refractive index resolution and high sensitivity to
molecular adsorbate would increase the scope of SPR-based technique by providing lower detection limits. A
potential solution may exploit micro-structured Au films. However, the plasmonic properties of micropatterned
metallic films are still relatively unknown. We have undertaken the study of the plasmonic properties from Au film
with features on the order of 1 to 3 μm. Microtriangle and microhole arrays were fabricated by modified nanosphere
lithography, consisting of a polymer microsphere mask deposited in a close-packed hexagonal monolayer, etched by
oxygen plasma. Etch time controls the diameter of the microhole and the initial microsphere diameter sets the
periodicity. Investigation of the SPR properties in the Kretschmann configuration was undertaken using a SPR with
a dove prism and a multi-wavelength scanning angle SPR. The sensitivity of SPR with microhole arrays exhibits an
improvement by a factor of 3 in comparison to SPR using a smooth Au film. This is accomplished by tuning the
angle to near 73 degrees (with a BK7 glass prism). Moreover, the sensitivity to the immobilization of an antibody
was improved by at least a factor of 4 as demonstrated with the kinetics of immobilization for IgY, without
employing secondary amplification techniques. No modification to the instrumentation is required and microhole
arrays improve resolution of the SPR response.
Sensing of bacteria immobilised under static conditions using long-range surface plasmon waveguides in Cytop
Author(s):
Asad Khan;
Oleksiy Krupin;
Ewa Lisicka-Skrzek;
Pierre Berini
Show Abstract
Waveguides consisting of Au embedded in Cytop with micro-fluidic channels etched into the cladding are used for
sensing via the propagation of long-range surface plasmons. Initially, a range of water/glycerol solutions with varying
refractive indices were sequentially injected in a waveguide section in order to assess its bulk sensitivity and to find a
solution supporting a strong high quality mode. Au waveguide surfaces were then functionalized with antibodies against
Gram negative bacteria (Anti-Gneg) by first forming a self-assembled monolayer (SAM) of 16-mercaptohexadecanoic
acid (16-MHA) and subsequent conjugation with antibodies through carbodiimide chemistry. E.Coli XL-1 Blue was
used as an analyte in static incubations. Wavelength sweeps of 16-MHA covered waveguides were compared against
waveguides covered with E-coli. The results indicate that very few bacteria cells are required to obtain a measurable
change in output signal.
Simultaneous 1310/1550 dual-band swept laser source and fiber-based dual-band common-path swept source optical coherence tomography
Author(s):
Youxin Mao;
Shoude Chang;
Erroll Murdock;
Costel Flueraru
Show Abstract
A simultaneous two wavelength band swept laser source and a fiber-based dual-band common-path swept source optical
coherence tomography is reported. Simultaneous 1310/1550 dual-wavelength tuning is performed by using two
fiber-ring cavities with corresponding optical semiconductor amplifier as their gain mediums and two narrowband
optical filters with a single dual-window polygonal scanner. Measured average output powers of 60 mW and 27 mW
have been achieved for 1310 and 1550 nm bands, respectively, while the two wavelengths were swept simultaneously
from 1227 nm to 1387 nm for 1310 nm band and from 1519 nm to 1581 nm for 1550 nm band at an A-scan rate of 65
kHz. A broadband 1310/1550 wavelength-division multiplexing is used for coupling two wavelengths into a
common-path single-mode GRIN-lensed fiber probe to form a dual-band common-path swept-source optical coherence
tomography. Simultaneous OCT imaging at 1310 and 1550 nm is achieved by using a depth ratio correction method.
This technique allows potentially for in vivo endoscopic high-speed functional OCT imaging with high quality
spectroscopic contrast with low computational costs. On the other hand, the common path configuration is able to reject
common mode noise and potentially implement high stability quantitative phase measurements.
Labview programming for swept-source full-field optical coherence tomography
Author(s):
Shoude Chang;
Youxin Mao;
Costel Flueraru
Show Abstract
Full-field optical coherence tomography (FFOCT) acquires image data in parallel. It has a big advantage in high-speed
imaging because 2-dimensional mechanical raster scanning in the sample arm, which is essentially needed in a common
fiber-based OCT system, does not exist anymore. Swept-source FFOCT (SSFFOCT) further makes the system free of
depth scanning that significantly increases the operation speed. National Instrument's LabVIEW is a powerful tool to fast
develop optical-electronic systems which have motion/vision units, signal processing functions and easy-to-generate
Graphic User Interface (GUI). In this paper, we describe the design and implementation of Labview program prepared
for an SSFFOCT system. Basically, there are four modules of Labview programming in such a system: 1. Wavelength
sweeping control; 2. Synchronized image grabbing; 3. SSFFOCT signal processing; 4. 3-dimensional tomogram
displaying mode selection. A general graphic user interface is used to input the parameters and monitor all necessary data
and curves. The tomographic images can be displayed at any given cutting direction. More details and examples are
provided and discussed.
Measurement of long-range surface plasmon-polariton devices in Cytop
Author(s):
Hui Fan;
Ewa Lisicka-Skrzek;
Pierre Berini
Show Abstract
Long-range surface plasmon-polariton (LRSPP) waveguide structures fabricated of gold stripes (5 μm wide and 35
nm thick) embedded in CYTOP were characterized. TM polarized 1310 nm light emerging from a polarisationmaintaining
optical fibre was injected into the structures via butt-coupling and the output light was measured so that
the loss could be calculated. Cutback measurements were carried out on straight waveguides so as to determine their
attenuation as well as the butt-coupling loss per facet. Various other passive elements were also characterized. The
results were compared with theoretical expectations and errors are surmised to be caused by fabrication
imperfections. Thermo-optic modulation measurements were also carried out on straight waveguides. These
elements are of interest for biosensors, where propagation through an aqueous solution (having an index of
refraction very close to that of Cytop) is necessary.
Synthesis and characterization of silver-PDMS nanocomposite for the biosensing applications
Author(s):
Jayan Ozhikandathil;
Simona Badilescu;
Muthukumaran Packirisamy
Show Abstract
Noble metal (Au, Ag, Pd) - PDMS composites show highly enhanced mechanical and optical properties compared with
the polymer alone. Among the different methods of synthesis, the in situ "one step" preparation of these composite
materials, by immersion of PDMS films into the solution of the metal salt and reduction to elemental metal is a simple
and straightforward method. The metal nanoparticles are immobilized and uniformly distributed into the surface layers
of the polymer and this structure proved to be suitable for biosensing purposes. Sensing is performed by measuring the
position and intensity of the Localized Surface Plasmon Resonance (LSPR) band of silver in the UV-Visible spectrum of
the nanocomposite. In this work, the structure and composition of Ag-PDMS nanocomposites are optimized in order to
enhance the sensitivity of the sensing platform. A novel method of tuning the morphology of nanocomposite by
annealing it for the desired optical property is optimized. The quality of the platform is investigated for sensing
polypeptides such as hormones, through an immunoassay, by using the antigen-antibody interaction.
Filamentation of femtosecond laser pulses as a source for radiotherapy
Author(s):
Ridthee Meesat;
Jean-François Allard;
Hakim Belmouaddine;
Tiberius Brastaviceanu;
Luc Tremblay;
Benoit Paquette;
Jean-Paul Jay-Gerin;
J. Richard Wagner;
Martin Lepage;
Daniel Houde
Show Abstract
Here, we report that intense ultra-short laser pulses produce a plasma of low energy electrons (LEEs) by the
inverse Bremsstrahlung effect and multiphoton ionization process. The phenomena show five striking characteristics.
First, the self-focusing of ultra-short laser pulses creates a plasma of LEEs (6.5 eV), which is concentrated in filaments
through an avalanche process. Second, kinetically hot 6.5 eV electrons interact with surrounding molecules resulting in
reactive radical species. Third, the dose rate reaches an enormous level of ~2.8 × 1011 Gy/s as determined by a cericcerous
sulfate dosimetry and this leads to an ultra-high deposition of energy of between 4.6 × 107 to 8.16 × 107 keV/μm.
Fourth, filaments of variable length are produced by femtosecond pulses depending on the pulse duration as determined
by a tissue-equivalent radiation polymer gel dosimeter and imaged by magnetic resonance imaging (MRI). These results
reveal that one of the very interesting novelty of filamentation is the very low entrance dose, similar to proton irradiation.
Lastly, filamentary irradiation results in the decomposition of thymidine in the absence and the presence of oxygen
similar to the radiolysis of water.
Sensitivity analysis of 1D and 2D photonic crystals sensors based on change of thickness and refractive index in material
Author(s):
Anil Kumar Mudraboyina;
Jayshri Sabarinathan
Show Abstract
A detail study was done on the sensitivities of 1-D photonic crystal (PC) and 2-D PC coupled cavity sensors with
changing sensing layer parameters of thickness and refractive index (RI). Though both refractive index and thickness are
interrelated they have significant individual affects on device response. In 1-D PC shifts in normal transmission peak due
to surface change in thickness and RI and in 2-D PC coupled cavity shifts in transmission dip due to surface changes are
observed. Here sensitivity analysis in change in thickness and RI on these devices was done for four cases; case 1:
change in thickness from 2nm-10nm on PC sensors, case 2: change in thickness from 75nm-175nm on PC sensors, case
3: change in RI in thin film (6nm) on surface and case 4: change in RI in thick film (100nm) on sensors surface.
Sensitivities due to change in thickness (St) of 1-D PC and 2-D PC coupled cavity were calculated from the slope of the
sensitivity curves and found to be (for RI of 1.4) 1.423nm/nm and 2.285nm/nm for case 1 and 0.455nm/nm and
0.801nm/nm for case 2. Sensitivities due to change in RI (Sr) of 1-D PC and 2-D PC coupled cavity were obtained from
the transmission peak and dip shifts due to change in RI from 1(air) to 2. Sr for 1-D PC and 2-D PC coupled cavity were
found to be 70nm/RIU and 103nm/RIU for case 3 and 143nm/RIU and 213nm/RIU for case 4. The results are based on
FDTD simulations.
Energy-efficient extensions in passive optical networks
Author(s):
Robert Radziwilowicz;
Jose Gama Benitez;
Trevor J. Hall
Show Abstract
The rapidly growing popularity of internet-based services has increased the number of end users that are connected to
access networks every year. Internet Service Providers (ISPs) have to deal with an increasing density of access networks
in urban areas and extended reach of the network in remote locations. Existing public network infrastructure requires
new energy efficient and cost effective extension technologies to accommodate new subscribers and to provide the
required bandwidth for new services such as High Definition TV or Video on Demand. This paper presents a study of the
low power Optical Semiconductor Amplifier (SOA). The most important characteristics of the SOA are presented and
compared with other technologies such as Erbium Doped Fiber Amplifier (EDFA). Aspects of the energy consumption
are discussed and potential problems related to the SOA implementation are presented.
160W single-mode single-frequency Yb-doped fiber laser with fiber Bragg grating inscribed by UV femtosecond exposure and two beam interference
Author(s):
Martin Becker;
Sven Brückner;
Eric Lindner;
Martin Leich;
Manfred Rothhardt;
Sonja Unger;
Hartmut Bartelt
Show Abstract
Fiber Bragg gratings (FBGs) are attractive as reflector elements in fully integrated all-fiber laser systems. Furthermore,
FBGs made with femtosecond laser technology allow to reduce splice connections in the fiber, since
no special photosensitive fibers are required. Fiber Bragg grating inscription with deep ultraviolet femtosecond
laser (267 nm) and two beam interferometry allows to target germanium-free and non-photosensitive fibers
while maintaining versatility in the choice of the output wavelength of the fiber laser. This concept offers the
potential of gratings with high spatial resolution, great flexibility and good homogeneity and complements the
methods of point-by-point inscription at 800 nm or of phase-mask inscription with 400 nm femtosecond laser
exposure. We report on the application of the interferometric fiber Bragg grating inscription technology to build
a grating-stabilized fiber laser with high beam purity. Output powers up 160 W have been achieved.
Growth and stability of UV and VIS femtosecond written fiber Bragg gratings in different rare earth doped fibers
Author(s):
Julia Fiebrandt;
Eric Lindner;
Martin Becker;
Sven Brückner;
Manfred Rothhardt;
Hartmut Bartelt
Show Abstract
Using femtosecond (fs) radiation and multi-photon absorption processes for fiber Bragg grating (FBG) inscription offers
the advantage of writing FBGs independent of the chemical fiber composition. Especially for fiber laser applications the
fabrication of FBGs integrated in rare earth doped fibers is a favorable option for monolithic fiber lasers. In this paper we
report on the growth and stability of femtosecond generated fiber Bragg gratings in different rare earth doped fibers. For
this purpose we use two different fs laser wavelengths at 266 nm and 400 nm and a modified Talbot- interferometer
setup for the generation of first order Bragg gratings. We study the growth characteristics of FBGs in terms of
reflectivity, Bragg wavelength and spectral grating width during the writing with UV and VIS fs radiation. For these
experiments fibers drawn in-house at the IPHT are used, which possess varying contents of Ytterbium and/or Cerium
with a comparable Phosphor and Aluminum co-doping and a standard geometry (125 μm cladding, 8-10 μm core
diameter). We observe different kinds of grating growth processes depending on the inscription wavelength and the
specific doping level of the fibers. It is possible to produce high reflective Type I gratings by UV fs exposure and high
reflective Type II gratings with higher temperature stability by VIS fs exposure. The transformation from Type I to Type
II gratings with a 400 nm inscription wavelength is studied in dependence on the exposure conditions. Our experimental
results underline the role of doping for fs material photosensitivity and for FBG inscription process.
Mid-infrared sources based on the soliton self-frequency shift
Author(s):
A. M. Al-kadry;
M. Rochette
Show Abstract
We have modeled the soliton propagation in an As2Se3 microwire coated with PolyMethyl MethAcrylate (PMMA) with
the purpose of optimizing the soliton self-frequency shift (SSFS). We provide the optimal waist diameter and initial
soliton energy required to maximize the wavelength shifting from a wavelength of 2.29 um through a 20 cm long
microwire. In light of the dynamics of a fundamental soliton, we provide the optimal uniform and nonuniform
microwires that maximizes the soliton frequency-shift. Finally, we propose an approach to avoid the dispersive waves
emission by which the soliton energy density maintain at the output of the system.
Single-longitudinal-mode fiber optic parametric oscillator based on Smith predictor control scheme
Author(s):
Ali Salehiomran;
Seyed-Rahi Modirnia;
Benoit Boulet;
Martin Rochette
Show Abstract
Fiber optical parametric oscillators are laser sources with multiple longitudinal modes arising from their cavity
length reaching several tens of meters. To reduce the noise due to multimode beating, the spacing between
neighboring modes is increased using a Smith predictor internal control scheme. The Smith predictor utilizes
a model of the dynamic behaviour of the system to deal with pure time delay and eliminate the effect of the
delay in the overall closed-loop system. Applying the smith predictor, the system can be made to operate in a
single-longitudinal mode, removing the excess modes. In this paper a linear model for operation of parametric
oscillator is proposed and based on that transfer function of Smith predictor enhanced parametric oscillator
is established. Numerical analysis of resulting transfer function will lead us toward single-longitudinal mode
operation.
A wideband frequency tunable optoelectronic oscillator incorporating a tunable microwave photonic filter based on a phase-shifted fiber Bragg grating
Author(s):
Wangzhe Li;
Jianping Yao
Show Abstract
A wideband and frequency-tunable optoelectronic oscillator implemented by employing a two-port optical phase
modulator and a phase-shifted fiber Bragg grating without using electrical microwave filters is proposed and
experimentally demonstrated. The key device is the phase-shifted fiber Bragg grating, which functions, in conjunction
with the phase modulator in the loop, to form a tunable high-Q microwave bandpass filter to perform frequency selection.
The central frequency of the microwave photonic filter can be tuned by tuning the wavelength of the incident light wave;
therefore, the oscillation frequency can also be continuously tuned. An experiment is performed. The generation of a
microwave signal with a frequency that is tunable from 6 to 14 GHz is demonstrated.
Ultra-wide-band coplanar waveguide based impedance transformer using slow-wave electrodes
Author(s):
Xia Yao;
Nicolas A. F. Jaeger
Show Abstract
This paper presents a new type of broadband impedance transformer loaded with capacitive fins (ITF) suitable for use in
the frequency range 10 GHz to 70 GHz. Compared with conventional, unloaded, tapered impedance transformers, these
ITF structures extend the impedance matching range and the operating bandwidth for the same amount of on-chip real-estate.
We have designed ITFs capable of impedance matching resistive loads from ~ 10 Ω to ~ 229 Ω, on a 650 μm
thick GaAs substrate over about a 60 GHz bandwidth. Design examples are used to demonstrate the flexibility of these
ITF structures.
Real-time interrogation of a linearly chirped fiber Bragg grating sensor based on chirped pulse compression using a Sagnac loop interferometer
Author(s):
Weilin Liu;
Jianping Yao
Show Abstract
A novel approach to interrogating in real time a linearly chirped fiber Bragg grating (LCFBG) sensor based on chirped
pulse compression using a Sagnac loop interferometer (SLI) with improved pulse compression performance is proposed
and experimentally demonstrated. The proposed system consists of a mode-locked laser (MLL), a SLI incorporating an
LCFBG, which makes the SLI have a spectral response with an increasing or decreasing free spectral range (FSR), a
dispersive element and a photodetector. The significance of using an SLI incorporating an LCFBG is its capability of
providing equal dispersion for two pulses traveling along the clockwise and counter-clockwise paths, which would
effectively avoid a non-complete temporal interference, and improves the pulse compression performance. When the
fiber sensor is experiencing a strain, the strain information would be conveyed to a wavelength shift caused by the Bragg
wavelength change, which is further transferred to the change of the FSR. An ultra-short pulse train generated by the
MLL would be spectrum shaped by the SLI, and the shaped spectrum would contain the information of the wavelength
change. The demodulation is performed in the time domain by mapping the spectrally shaped waveform to the temporal
domain using a dispersion compensating fiber (DCF) as the dispersive element. The generated temporal waveform is
then correlated with a special reference waveform, with the location of the correlation peak indicating the wavelength
change which reflects the strain or temperature change. A theoretical analysis is carried out, which is validated by an
experiment. The experimental results show that the proposed system can provide an interrogation resolution as high as
0.22 με at a speed of 48.6 MHz with a correlation peak to sidelobe ratio of 2.5.
Super-radiance and fluorescence are two approaches to laser cooling of solids
Author(s):
Galina Nemova;
Raman Kashyap
Show Abstract
A new approach to cool solids with super-radiance (SR) pulses is presented in comparison with laser cooling based on
traditional anti-Stokes fluorescence. Contrary to the anti-Stokes fluorescence, which is in-coherent radiation
propagating in all directions around a sample, SR is the coherent, sharply directed spontaneous emission of photons by a
system of excited ions. We consider an Yb3+ doped ZBLAN sample pumped at the wavelength 1015nm with a
rectangular pulsed source. The intensity of the SR is proportional to the square of the number of excited ions. This
unique feature of SR permits an increase in the rate of the cooling process in comparison with the traditional laser
cooling of the rare earth doped solids with anti-Stokes fluorescence. This scheme overcomes the limitation of using only
low phonon energy glasses for laser cooling.
Pulsed laser deposition of Si nanodots for photonic applications
Author(s):
Manisha Gupta;
Fatema Rezwana Chowdhury;
Vincent Sauer;
Seong Shan Yap;
Turid Worren Reenaas;
Ying Yin Tsui
Show Abstract
Several growths of Si nanodots on Si and GaAs substrates were conducted by pulsed laser deposition (PLD) using a KrF
laser of 248nm, 15ns, 12Hz and a Ti-sapphire laser of 800nm, 130fs, 1kHz at 1x10-5mbar vacuum. The laser fluencies on
a Si target were varied from 3 to 32J/cm2 for the nanosecond (ns) PLD growths and 1-2.75J/cm2 for the femtosecond (fs)
PLD. Wide range of nanodots from 20nm to a few micron size droplets were observed from both the ns and fs PLD.
Auger electron spectroscopy of the nanodots was conducted and which indicated that the nanodots were without
contamination.
A technique using a mask consisting of an array of small holes was used to obtain high density nanodots with uniform
size. The array of 100nm diameter holes was created by E-beam lithography. With this technique we have achieved
100nm Si dots with 300nm spacing between them, with few defects. We have observed that laser fluences closer to the
ablation threshold work better for deposition using the EBL mask. In summary, we have demonstrated the growth of
100nm Si nanodots in an array with very few defects using the EBL masking technique.
Using optical tweezers to study mechanical properties of collagen
Author(s):
Naghmeh Rezaei;
Benjamin P. B. Downing;
Andrew Wieczorek;
Clara K. Y. Chan;
Robert Lindsay Welch;
Nancy R. Forde
Show Abstract
The mechanical response of biological molecules at the microscopic level contributes significantly to their function.
Optical tweezers are instruments that enable scientists to study mechanical properties at microscopic levels. They are
based on a highly focused laser beam that creates a trap for microscopic objects such as dielectric spheres, viruses,
bacteria, living cells and organelles, and then manipulates them by applying forces in the picoNewton range (a range that
is biologically relevant). In this work, mechanical properties of single collagen molecules are studied using optical
tweezers. We discuss the challenges of stretching single collagen proteins, whose length is much less than the size of the
microspheres used as manipulation handles, and show how instrumental design and biochemistry can be used to
overcome these challenges.
Laser-based proton acceleration on ultrathin foil with a 100-TW-class high intensity laser system
Author(s):
S. Fourmaux;
S. Buffechoux;
S. Gnedyuk;
B. Albertazzi;
D. Capelli;
L. Lecherbourg;
A. Lévy;
P. Audebert;
D. Houde;
R. Marjoribanks;
F. Martin;
H. Pépin;
J. Fuchs;
J. C. Kieffer
Show Abstract
Focusing a high intensity laser pulse, onto a thin foil target generates a plasma and energetic proton and ion beams from
the target rear and front sides, propagating along the target normal. Such laser produced collimated and energetic protons
beams are of high interest because of the wide range of applications: ion based fast ignitor schemes, probing of
electromagnetic fields in plasma, isotopes production or hadron therapy. The 100 TW class laser system at the Advanced
Laser Light Source facility, is used with an intensity close to 1019 W/cm2, to study protons acceleration with
femtosecond laser pulses, ultra thin foil target and high contrast laser pulse ratio. To characterize the plasma expansion,
we monitor it with an imaging technique using a femtosecond laser probe. In this configuration we were able to reach a
proton critical energy of 12 MeV and to work with target foil thickness as small as 15 nm.
Fiber Bragg grating sensor and waveguide grating sensor
Author(s):
Pin Long
Show Abstract
Several new designes of different type fiber Bragg grating(FBG) sensors, including long range strain sensor, pressure
sensor, and displacement sensor, have been introduced. A new concept of sliced fiber Bragg grating as free space
optical element has been presented. Some new waveguide Bragg grating writing technologies have been introduced.
Green light generation based on periodically poled LiNbO3 waveguides
Author(s):
Chang-qing Xu;
Jian Sun;
Yi Gan
Show Abstract
Periodically poled lithium niobate (PPLN) waveguide based green lasers have attracted much attention in the past years
due to their excellent properties, such as high efficiency and small size. The potential application fields include laser
display, bio-instrumentation, undersea communication and so on. In this paper, recent progresses on the development of
PPLN waveguide based green lasers are introduced and reviewed.
Waveguide crossing characterization for silica planar lightwave circuits
Author(s):
D. Celo;
P. Dumais;
S. Paquet;
J. Seregelyi;
C. Callender
Show Abstract
Optical waveguide crossings based on silica-on-silicon technology are investigated. The effect of crossing angle
(θ) on light transmitted at through and cross-port on a sequence of waveguide crossings with angle varying from
7 to 28° is modeled and experimentally validated. Results demonstrate that structures with small footprint
(θ≈9°) can achieve low crosstalk of -32 dB with high throughput, insensitivity to wavelength of operation, low
polarization dependent loss of 0.6 dB, and low sensitivity to fabrication tolerances. As a result, waveguide
crossings with small crossing angle present an attractive approach to reducing the overall component footprint
without compromising the performance.
Thermo-optic silica PLC devices for applications in high speed optical signal processing
Author(s):
Chantal Blanchetiere;
Claire L. Callender;
Sarkis Jacob;
Christopher J. Ledderhof;
Patrick Dumais;
Dritan Celo;
Lawrence R. Chen;
Payman Samadi
Show Abstract
The optimization of a 2×2 silica-on-silicon Mach-Zehnder interferometer (MZI) thermo-optic switch is presented. The
device consists of 2 multimode interference (MMI) couplers as splitter and combiner with metal heater strips for phase
control. The switching characteristics of the devices have been examined in detail as a function of several parameters.
The electrical power consumption of the switch has been reduced by a factor of 2 by etching trenches alongside the
waveguide heaters located on the arms of the MZI, and the polarization dependent loss has been controlled and reduced
through adjustment of top cladding properties. The effect on the response time of the switch of these design changes has
been investigated. Detailed characterization of the devices will be presented, and trade-offs in optimization discussed.
Incorporation of these device elements into increasingly complex components for new applications in optical signal
processing will be demonstrated.
A pressure sensor using tapered optical fiber and curved polymer films
Author(s):
X. Dai;
H. Ding;
C. Blanchetiere;
S. J. Mihailov
Show Abstract
A pressure or touch sensor is proposed by using a tapered optical fiber and polydimethylsiloxane (PDMS)
curved films. Under pressure, the light in the tapered optical fiber is partially leaked into the films by the
evanescent field properties. The optical attenuation of the tapered optical fiber is directly related to the
pressure change and sensitive to the profile of the film. By monitoring the change of the transmitted optical
power of the tapered optical fiber, the change of pressure is measured.
Planar lightwave circuits: it's all in the cladding
Author(s):
Patrick Dumais;
Claire Callender;
Jia Jiang;
Chantal Blanchetière;
Dritan Celo;
Sarkis Jacob;
Chris Ledderhof
Show Abstract
The top cladding layer in planar lightwave circuits (PLC) is more than an optical buffer. By variously doping, adjusting
the thickness of, etching patterns in and annealing the cladding layers in waveguide devices, a wide range of sensors and
photonic devices can be realized. The material properties of the cladding determine, for instance, the modal
birefringence of the waveguides; knowledge and control of these properties can be harnessed to produce polarization-independent
components. The fabrication of thermo-optically controlled switches and interferometers for tunable
filtering and optical signal processing is possible through the creation of micro heaters on top of the cladding. The
optimization of such components can benefit from engineering of the cladding, ranging from better planarization and
thickness control, to selective etching to better confine the heat distribution and provide stress relief. In addition, the
thermal properties of a given device can be radically enhanced by using a polymer layer as top cladding, which yields an
order of magnitude increase in the temperature sensitivity, an invaluable enhancement that can be harnessed for phase-tunable
waveguides or sensor structures. Long period gratings (LPGs) can be etched in the lower cladding to provide
filtering, signal processing, or sensor functions. In a borophosphosilicate cladding, typically used in silica-on-silicon
PLCs, control of the reflow properties through composition can be exploited to manufacture fillable microchannels that
are monolithically integrated with solid-core devices, enabling a unique platform for sensing, signal processing, or
nonlinear optics.
Simultaneous slow light, fast light, and continues slow to fast light tuning in a microresonator via interaction of dual inputs
Author(s):
Hiva Shahoei;
Jianping Yao
Show Abstract
A simple structure is proposed to generate slow and fast light simultaneously in a double-waveguide coupled disk
resonator (DCDR) launched with dual contra-propagating inputs. The interaction between the intra-cavity backscattering
and the losses out of cavity are investigated for the disk resonator while random surface defects (backscatters) are
intentionally introduced in the cavity to produce the backscattering. The theoretical investigation done in this work
shows that by adjusting the amplitude and/or phase difference between the dual inputs the interaction between the cavity
modes and backscatters can be controlled thus the transmission and dispersion of the output lights of the system can be
manipulated. This scheme is attractive for slow and fast light tuning applications especially when active tuning elements
such as a p-i-n diode or a heater is absent in the cavity.
Vertically coupled Si-based athermal double-ring biosensor
Author(s):
Yule Xiong;
Winnie N. Ye
Show Abstract
A silicon-based athermal double-ring resonator biosensor with a vertically coupled configuration is developed. We
present an optimal design of the sensor structure by specifying the radii of the reference and the sensing rings, the
vertical coupling offset, d, between the two rings and the bus waveguide, and the lateral offset, l, between the edges of
the rings and the bus waveguide. By using Lumerical software package, we demonstrate that the optimal vertical and
lateral offsets are d=325 nm and l=-80 nm, respectively. One major challenge faced by ring based biosensors is their
temperature dependent characteristics. In this study, the sensing ring is exposed to the biomaterial under test, while the
reference ring provides a temperature-insensitive reference to the sensing measurements. By assuming the biomaterial
medium has small variations in temperature, we conclude that the proposed biosensor device offers temperature
insensitive measurement, where the temperature effects are fully corrected by the reference ring response. The double-ring
sensors are proposed to be fabricated with the local oxidation of silicon process, without the need for advanced
lithography methods such as e-beam or deep UV lithography. In addition, the vertically coupled double-ring
configuration allows precise control of the critical coupling separation between the rings and the bus waveguide. The
proposed silicon double-ring biosensor can be used for highly sensitive and stable sensing for both biomedical and
environmental applications.
Graded index MMI and its application in optical communications
Author(s):
Mohamed A. Swillam;
Mohamed H. Bakr;
Xun Li
Show Abstract
We present the details and characteristics of graded index multimode mode interference (GIMMI) and its applications in optical communication components. This structure has unique features that allow for less sensitive wavelength dependant than the step Index case. This feature allows for wideband applications. In this paper, we present the applications of this structure to design wideband ultrafast integrated optical switch and integrated wideband polarization splitter. The graded index effect is produced using stair case index profile that mimics the parabolic index profile. The MMI with parabolic index profile has the analytical expression for the imaging length which provides simple design equations for the whole structure. The accuracy of this model is verified using 3D full vectorial beam propagation method.
Designing a nanometer-scale light bending structure
Author(s):
M. W. Maqsood;
K. J. Chau
Show Abstract
The emergence of nanotechnology now enables the controlled fabrication of nanometer scale structures capable
of steering and confining light waves over small distances. To realize complex nanoscale light guiding structures, it will
be necessary to develop methods to guide light around tight bends and corners with high efficiency. Achieving high
efficiency waveguide bends, however, is generally difficult because of radiation losses at the bend. To achieve tight
waveguide bends several approaches have been put forward including the use of dielectric photonic crystals and
resonators. One recent and promising method to limit the amount of loss over a bend is to restrict the path of light by
encasing a bend in an opaque medium, such as metal. Such a bend can be conceptualized by joining the two metal-dielectric-
metal (MDM) waveguides such that their dielectric cores are connected to each other at 90° as shown in
Fig. 1. When the thickness of the dielectric cores is subwavelength, only the lowest order surface plasmon polariton
(SPP) mode is sustained by the bend. Further, when the metal walls are constructed from a low-loss metal such as Ag,
the SPP mode can propagate over the bend.
Imaging properties of different refractive axicons
Author(s):
Andrew Saikaley;
Sofia Matoug;
Ilya Golub;
Brahim Chebbi
Show Abstract
The extended depth of field of axicons is an advantage for imaging applications but comes with a degradation of image
quality. Image processing is proposed to solve this problem. In the present work, three types of refractive axicons are
examined for imaging applications: a linear axicon, a logarithmic axicon and a Fresnel axicon. Each one has its own
advantages: a linear axicon is simple, the Fresnel axicon is compact and has a potential low cost of production and the
logarithmic axicon generates nearly constant longitudinal intensity distribution which might ensure a more uniform
image quality along the focal length. Preliminary experimental measurements of the Point Spread Function (PSF) for
each one of these axicons were performed and are used to design digital filters to de-noise the images.
Performance comparison between silicon-on-insulator curved waveguides and corner turning mirrors
Author(s):
Qi Zheng;
Imad Hasan;
DeGui Sun;
Sawsan Abdul-Majid;
Trevor J. Hall
Show Abstract
Silicon-on-insulator (SOI) photonic integrated circuits have recently become a research topic of great interest due to their
compact confinements and compatibility with the modern micro-electronics. As the dominant issues of the integration
density of planar lightwave circuits on a single SOI chip, low-loss SOI curved waveguides and corner turning mirror
(CTM) structures are attracting attention. This work aims at the performance comparison between the SOI curved
waveguides and CTM structures. For this goal we have designed both SOI curved waveguides and SOI CTM structures
and then fabricated them. The performance of these two devices, such as the propagation loss and polarization dependent
loss, is measured and compared.
SOI back reflector for Tb-doped oxide electroluminescent devices
Author(s):
Harjinder Singh Saini;
T. W. MacElwee;
A. Rankin;
J. Wojcik;
A. M. Miles;
N. G. Tarr;
P. Mascher
Show Abstract
Electroluminescent devices based on light emission from Tb-doped SiO2 incorporated in a MOS capacitor
structure have been formed on SOI substrates. It is shown that with appropriate choice of Si film and buried oxide
thickness the SOI substrate can serve as a quarter-wave high-low-high index back reflector. Analysis predicts this back
reflector can boost total light output integrated over the Tb emission spectrum by approximately 35% compared to a bulk
substrate control device. Experimental devices using 100 nm thick PECVD SiO2 emitting layers doped with 1% Tb were
fabricated on substrates with nominal 32 and 108 nm Si film thickness (corresponding to approximately λ/4 and 3λ/4 at
the Tb emission peak). The Si films were doped to 1019 - 1020 cm-3 by As implantation. Uniform bright green
electroluminescence was obtained from 250 μm square devices, demonstrating that current crowding is not an issue even
with such a thin Si film. The comparison of output spectra for thick and thin Si films demonstrates that optical
absorption in the heavily doped Si film does not seriously degrade the light output of the devices.
Reflection mode two-dimensional photonic-crystal-slab-waveguide-based micropressure sensor
Author(s):
Yi Wang;
Aref Bakhtazad;
Jayshri Sabarinathan
Show Abstract
Photonic crystals (PhCs) have recently been the focus for the developing micro- and nano-optical sensors, due to its
capability to control and manipulate light on planar devices. This paper presents a novel design of micro-optical pressure
sensor based on 2-dimensional PhC slab suspended on Si substrate. A line defect was introduced to the PhC slab to guide
and reflect light with frequency in the photonic bandgap in the plane of the slab. The structure, with certain surface
treatment, can be used in miro-scale pressure catheters in heart ablation surgeries and other biomedical applications. The
working principle of the device is to modify light reflection in the PhC line defect waveguide by moving a substrate
vertically in the evanescent field of the PhC waveguide. Evanescent field coupling is the critical step that affects light
transmission and reflection. High resolution electron-beam lithography and isotropic wet etching have been used to
realize the device on the top layer of a Si-On-Insulator (SOI) wafer. The PhC slab is released by isotropic wet etch of the
berried oxide layer. The output reflection spectrum of the device under different pressure conditions is simulated using
3-dimensional finite difference time domain (FDTD) method. The result showed that when the PhC slab is close enough
to the substrate (less than 400 nm), the reflected light intensity decreases sharply when the substrate moves towards the
PhC slab. Mechanical response of the sensor is also studied.
Light filtering using subwavelength periodic structures on polymer material
Author(s):
Sasan V. Grayli;
Badr Omrane;
Clinton Landrock;
Bozena Kaminska
Show Abstract
In this work, the diffractive capability of nano-scale gratings fabricated on transparent substrates is
investigated. Nano-hole arrays of 9 to 20 mm2 with 450 nm, 550 nm and 650 nm periodicities were milled on 5
nm-thick chromium coated sheet of polyethylene terephthalate (PET) substrates using a focused ion beam
(FIB) to create periodicity-dependent diffraction patterns. Based on the method with which the diffraction
pattern was measured a new technology is proposed in which the optical signals are used to encode
information.
Angle dependent far-field spectroscopy on nanohole arrays
Author(s):
Sasan V. Grayli;
Badr Omrane;
Clinton Landrock;
Bozena Kaminska
Show Abstract
In this work the dependency of the transmitted spectrum through arrays of nano-holes on the angle of
incident light was investigated. The arrays of nano-holes fabricated on thin aluminum (Al) layer which was
deposited on a quartz substrate were used to observe how change of the angle of incident light could change
the peak of transmitted spectrum. Through far-field spectroscopy it was shown that the transmitted spectrum
is detectable at the distances beyond 20 cm.
Electronic mitigation of fiber transmission impairments in 100Gbit/s WDM phase encoded transmission with optical add-drop multiplexers
Author(s):
Rameez Asif;
Chien-Yu Lin;
Muhammad Usman;
Michael Holtmannspoetter;
Bernhard Schmauss
Show Abstract
Digital Backward Propagation (DBP) algorithm for mitigating fiber dispersion and non-linearities based on modified
non-iterative symmetric split-step Fourier method (M-SSFM) is implemented and numerically evaluated.
The algorithm is modified by shifting the calculation point of non-linear operator (r) together with the optimization
of dispersion (D) and non-linear coefficient (γ) to get the optimum system performance. DBP is evaluated
for 10x10Gbit/s wavelength division multiplexed (WDM) system (a total transmission capacity of 100Gbit/s)
with RZ-DQPSK encoded signals over a transmission length of 1600km standard single mode fiber (SMF) with
no in-line optical dispersion compensation. Furthermore, we quantify the impact of optical add-drop multiplexers
(OADMs) in the transmission link. Modification of DBP parameters and bandwidth of optical filters associated
with OADMs give significant improvement in the system performance.
Photodeterioration and recovery treatment for silicon nanocrystal luminescence
Author(s):
R. Karmouch;
D. Barba;
D. Koshel;
F. Martin;
G. G. Ross
Show Abstract
Silicon nanocrystals (Si-nc) embedded in silica exhibit intense visible photoluminescence (PL) at room temperature.
However, under continuous wavelength (CW) laser excitation at 405 nm, the Si-nc PL intensity decreases with time,
approximately with two decay constants. The fast decay component is unchanged by repetitive laser exposures, it is
related to the local sample heating induced by the laser. The slower time constant corresponds to a permanent decrease
of the PL emission. This photodeterioration strongly affects the precision of optical gain measurements using VSL
(Variable Stripe Length) or P&P (Pump and Probe) techniques, hindering the development of Si-nc technology for
photonics applications. In this context, a procedure that would restore the PL intensity of Si-nc samples or minimize this
deterioration is highly desirable. UVC light (254 nm) irradiation of samples followed by an annealing at different
temperatures for 1 h under nitrogen flux increases the PL emission of Si-nc embedded in silica that have been previously
exposed to a CW laser pumping. Although this procedure does not prevent the decrease of the PL intensity associated
with the increase of sample temperature under CW pumping (the fast decay component), it contributes significantly to
reduce the permanent deterioration of the PL intensity. This procedure can also be applied to non-irradiated samples. The
PL emission collected from treated samples was studied as a function of laser irradiation time, and compared to that of
non-treated samples. The resistance to degradation of light-emitting silicon nanocrystals can be increased by UVC
irradiation followed by annealing at an optimal temperature of 400 °C under nitrogen environment. Following this
treatment, a reliable optical gain measurement can be performed once the local heating has been stabilized (the fast
decay component).
Reducing the energy consumption of the reliable design of IP/WDM networks with quality of protection
Author(s):
Burak Kantarci;
Hussein T. Mouftah
Show Abstract
Energy consumption of the telecommunication networks contributes to a large portion of the greenhouse gas
(GHG) emissions due to the global electricity consumption. Furthermore, backbone networks dominate the
energy consumption of the telecommunication networks by high peak data rates. In this paper, we enhance
our previously proposed energy-efficient availability design scheme for IP over WDM (IP/WDM) networks, i.e.,
Power-Aware Reliable Design (PARD).1 Here, PARD-QoP is proposed which incorporates Quality of Protection
(QoP) with power-aware reliable IP/WDM Network design. According to the QoP concept, each connection
demand specifies a working bandwidth capacity requirement and a minimum backup capacity requirement. We
evaluate the performance of PARD-QoP under the 14-node NSFNET topology for six QoP classes that are
uniformly distributed among the connection requests and for various demand sizes. The simulation results show
that PARD-QoP enhances its predecessor PARD by 7%-12% in terms of Capital Expenditure (CAPEX), denoting
the number of wavelength channels, and by 4%-8% in terms of Operational Expenditure (OPEX), denoting the
energy consumption. Moreover, PARD-QoP is shown to differentiate the demands in three availability classes as
99.9%, 99.99% and 99.999% with respect to the backup bandwidth requirements.
A two-phonon regime of operating an advanced prototype of a multichannel acousto-optical spectrometer for the Mexican Large Millimeter Telescope
Author(s):
Alexandre S. Shcherbakov;
Daniel Sanchez Lucero;
Karla J. Sanchez Perez;
Abraham Luna Castellanos
Show Abstract
Practical applications to both ground-based and satellite exploitations have demonstrated that acousto-optical spectrum
analyzers of radio-signals represent really reliable signal-processing technique for the millimeter radio-astronomy.
These spectrometers provide sufficiently high efficiency of operation together with the frequency resolution needed for
astronomic observations. The basic component of similar spectrometer is the acousto-optical cell, whose operation is
based on its ability to shape large amount of independent dynamic diffractive gratings. Each of them reproduces the
amplitude, frequency, and phase of only one spectral component from the signal under analysis. A multi-pixel CCD
linear array detects the obtained responses in Fourier plane of the integrating lens. The main peculiarity of this
prototype lies in exploiting a large-aperture tellurium-dioxide crystalline acousto-optical cell, oriented almost along the
[001]- and [110]-axes. This cell allows a two-phonon light scattering providing the improved frequency resolution in
comparison with conventional one-phonon regime. This fact determines technical requirements to the framing sub-systems
and performances of the prototype as a whole. Due to rather high anisotropy of tellurium dioxide, the
efficiency of both one- and two-phonon light scattering depends essentially on the ellipticity of the incident light
polarization, so that high-efficient operation needs the eigen-state elliptic polarization, which is determined by the
incidence angle, light wavelength, and accuracy of the cell's crystallographic orientation. Currently, an advanced
prototype has used a green laser beam at 532 nm with central acoustic frequency about 52 MHz. The first trial
experiments in a two-phonon light scattering regime have shown frequency resolution of about 30 KHz.
A new methodology for optical sensing and identification using optical-disc drives
Author(s):
Samuel Schaefer;
Kenneth J. Chau
Show Abstract
Optical disc drives are inexpensive, readily available, and use highly sophisticated optoelectronic components which can
be adapted for sensing. One limitation of using compact discs (CDs) and optical disk drives for sensing of analytes
placed on a CD is the fluctuations in the voltage signal from the disk drive generated while reading the data on the CD.
In this study, we develop a simple, low-cost strategy for sensing and identification using CDs and optical disk drives that
spectrally separates contributions to the voltage signal caused by an analyte intentionally placed onto the CD and that
caused by the underlying data on the CD. Analytes are printed onto a CD surface with fixed spatial periodicity. As the
laser beam in an optical disk drive scans over the section of the CD containing the analyte pattern, the intensity of the
laser beam incident onto the photodiode integrated into the disk drive is modulated at a frequency dependent on the
spatial periodicity of the analyte pattern and the speed of the optical disk drive motor. Fourier transformation of the
voltage signal from the optical disk drive yields peaks in the frequency spectrum with amplitudes and locations that
enable analyte sensing and identification, respectively. We study the influence of analyte area coverage, pattern
periodicity, and CD rotational frequency on the peaks in the frequency spectrum associated with the patterned analyte.
We apply this technique to discriminate differently-coloured analytes, perform trigger-free detection of multiple analytes
distributed on a single CD, and detect at least two different, overlapped analyte patterns on a single CD. The extension
of this technique for sensing and identification of colorimetric chemical reagents is discussed. Future work will focus on
adapting this technique to perform measurements at multiple wavelengths and streamlining the data collection and
processing.
Naturally occurring tenebrescent materials gives insight into the development of optically active materials whose attributes are controlled by two dopants
Author(s):
Domenic Olivieri
Show Abstract
An optical material encountered during ongoing field collection activities displays tenebrescence, fluorescence
and photo-refractive properties. The material is an uncommon variety of sodalite called hackmanite. It is part of the
tectosilicate family, a type of silca-based polymer structure, which was discovered to accommodate two separate dopant
sites within close proximity to each for fast carrier mobility. The dopants serve to either create vacancies or donors of
electrons within the material, thus providing the carriers to be manipulated. Variations of these materials can be found
in either an isometric (hackmanite) or asymmetric (marialite) forms providing for application in the development of
nonlinear optical devices, i.e. frequency mixers or harmonic sum or difference generation. Also discovered were results
that indicated a lack of sulphur being present, contrary to previous publications.
High performance multimode interference couplers for coherent communications in silicon
Author(s):
R. Halir;
G. Roelkens;
A. Ortega-Moñux;
J. G. Wangüemert-Pérez;
I. Molina-Fernández
Show Abstract
We review the need for coherent optical communication systems and briefly describe the receiver frontend they require.
The key element of the receiver is an optical 90° hybrid, which combines the received signal with the local oscillator
laser with the adequate amplitude and phase relations. Silicon technology offers several advantages for the realization of
such devices: compactness and CMOS compatibility, among others. However, the realization of high-performance
hybrids is hampered by the high index contrast of this technology. We show that using multimode interference couplers
with fully etched access waveguides and a shallowly etched multimode region, ultra-compact, high performance 90° hybrids can be realized. We experimentally demonstrate a device with a phase error below 5° and a common mode
rejection ratio better than -20dBe in a ~50nm bandwidth.
Modelling of optical trapping
Author(s):
Martin Šiler;
Vítězslav Karásek;
Oto Brzobohatý;
Tomáš Čižmár;
Pavel Zemánek
Show Abstract
After more than thirty years after Arthur Ashkin's pioneering experiments the optical trapping is a widely
established technique of the modern science. Its applications cover wide range of physics, chemistry and biology.
In many of these applications the irregular, inhomogeneous or ensembles of many particles are exposed to the
light fields where such particles could be stably confined. In this paper we will present results of several numerical
methods that describe optical forces acting on particles placed in the non-diffracting Bessel Beam.
Slow-light enhanced spectrometers on chip
Author(s):
Zhimin Shi;
Robert W. Boyd
Show Abstract
We propose using slow light structures to greatly enhance the spectral performance of on-chip spectrometers.
We design a calzone photonic crystal line-defect waveguide which can have large group index over a certain
wavelength range. An arrayed waveguide gratings (AWGs) is studied as an example, and the performance of
such a slow-light AWG is analyzed numerically.
Systematic approach for tolerance analysis of photonic systems
Author(s):
J. F. C. van Gurp;
M. Tichem;
U. Staufer
Show Abstract
Passive alignment of photonic components is an assembly method compatible with a high production volume. Its
precision performance relies completely on the dimensional accuracies of geometrical alignment features. A tolerance
analysis plays a key role in designing and optimizing these passive alignment features. The objective of this paper is to
develop a systematic approach for conducting such tolerance analysis, starting with a conceptual package design, setting
up the tolerance chain, describing it mathematically and converting the misalignment to a coupling loss probability
distribution expressed in dB. The method has successfully been applied to a case study where an indium phosphide (InP)
chip is aligned with a TriPleX1 (SiO2 cladding with Si3N4 core) interposer via a silicon optical bench (SiOB).
Retrieval of diffusing surface by two-frame interferometric method with blind phase shift of a reference wave
Author(s):
Leonid I. Muravsky;
Arkady B. Kmet';
Taras I. Voronyak
Show Abstract
Two-frame interferometric method with blind phase shift of a reference wave for smooth surfaces retrieval is
considered. The ability of this method to reconstruct a macrorelief of diffusing surfaces with a given roughness is
studied. Computer simulations have testified the ability of reliable low-noise reconstruction of the diffusing surface
macrorelief with standard deviation of the roughness heights up to λ/10 by using the developed interferogram
processing algorithm. The simulations have shown that the proposed correlation approach, which is used to determine
the reference wave blind phase shift, is more suitable for a diffusing surface than for a smooth one and the increase of
surface roughness leads to a quadruple decrease of this error in comparison with that for the smooth surface.
Experimental verification of the interferometric method performance to retrieve real diffusing surface macroreliefs
with given roughness has been done by using the experimental setup based on a Twyman-Green interferometer and
roughness comparison specimen. The obtained experimental results virtually have coincided with the computer
simulation results that prove the performance of the considered method to retrieve not only smooth, but also diffusing
surfaces.
Design of hydrogen gas sensors based on surface plasmon waveguides
Author(s):
Norman R. Fong;
Pierre Berini;
R. Niall Tait
Show Abstract
The use of hydrogen (H2) as a clean energy source is gaining significant global interest. Hydrogen gas can be
combustible in air at concentrations starting at 4%, so a low cost, compact and reliable leak detector for hydrogen gas
integratable into systems is desired. A Long Range Surface Plasmon Polariton (LRSPP) membrane waveguide structure
is discussed as a hydrogen sensor. Palladium on a silicon dioxide free-standing membrane is proposed as the waveguide
structure. Palladium absorbs hydrogen thereby inducing a detectable change in its permittivity. The design of straight
waveguide and Mach-Zehnder Interferometer (MZI) architectures are discussed. Finite element method (FEM)
simulations are conducted to choose appropriate designs to maximize sensor sensitivity.
The effect of the target size on the optical response of ultrafine metallic spherical particles arranged in a two-dimensional array
Author(s):
Mohammed Alsawafta;
Mamoun Wahbeh;
Sushil Misra;
Vo-Van Truong
Show Abstract
Discrete Dipole Approximation (DDA) is a computational technique to simulate the optical properties of nanostructures
of different shapes, sizes, and compositions. The influence of the target size on the optical response of 5 nm-diameter
nanoparticles arranged in a monolayer hexagonal array is investigated by using DDA at various incident angles of the
incident light on the target considered for silver (Ag), gold (Au) and copper (Cu) nanoparticles. In our study, the target
size is controlled by the number of the spherical nanoparticles used to generate the two dimensional arrays. The
interparticle distance is kept constant in all the simulations. The anisotropic response of noble-metal nanoparticles is
generally characterized by the excitation of the high-energy (transverse) surface plasmon (SP) mode and the low-energy
(longitudinal) SP mode. Results of the simulations for the three chosen metals show an exponential dependency of the
absorption efficiency of the SP modes with respect to the target size. As the target size is increased, the energy of Ag-longitudinal
SP mode is red-shifted and it displays an exponential decay while the band position of the transverse mode
is blue-shifted. They however overlap when the smallest target size is considered. Although, the optical response of Au
and Cu nanoparticle arrays shows the same dependency on the target size as observed in the case of Ag, the positions of
their respective longitudinal and transverse modes are very close, making these almost indistinguishable. The
dependency of the absorption efficiency of SP modes on the incident angle is fitted linearly for Cu, Au and longitudinal-
Ag modes to the target size, while the transverse-Ag mode shows an exponential fitting. No change in the Ag-SP band
position is observed when the incident angle is changed, but the SP bands for both Au and Cu exhibit exponential
variation behavior.
Optical properties of two-dimensional and three-dimensional arrays of noble metal nanoparticles by the discrete dipole approximation method
Author(s):
Mamoun Wahbeh;
Mohammed Alsawafta;
Sushil Misra;
Vo-Van Truong
Show Abstract
The optical aspects of plasmon coupling occurring through the near-field interactions among metallic spherical
nanoparticles assembled in close proximity to each other in two-dimensional and three-dimensional arrays have been
examined using the discrete dipole approximation (DDA). Calculations were performed for nano-sized close-packed
spheres of silver, gold or copper, hexagonally arranged in a planar monolayer target and extended gradually to three-dimensional
multilayer targets with a fastened interparticle spacing. Those targets were simulated under the incident ppolarized
light with an energy range of 1.5 - 4.5 eV by executing an open-source code of the DDA. The optical response
of three-dimensional targets was revealed in the absorption spectra calculated at various angles of the polarized incident
light, showing a blue shift of the plasmon resonance (PR) peak for both gold and copper targets. The splitting of the
surface plasmon resonance (SPR) observed in the response of the two-dimensional silver system eventually disappeared
into one well-defined resonance peak as the system grew in the third dimension. Moreover, to shed light on the nature of
the plasmon coupling among close-packed nanospheres of different metals, we simulated a target composed of mono-sized
nanospheres of the three metals placed spatially in three consecutive layers. A combined optical behaviour was
thus observed through the absorption spectrum, where the plasmon peaks attributed to the silver, gold and copper
interacting nanospheres emerged at the original energy values as if it was applied in isolated planar hexagonal arrays.
Design of spectrometer for high-speed line field optical coherence tomography
Author(s):
Mohammad Kamal;
Sivakumar Narayanswamy;
Muthukumaran Packirisamy
Show Abstract
The quality of the spectrometer affects the sensitivity fall-off, axial resolution, and depth scan range, therefore overall
performance of the spectral domain optical coherence tomography (SD-OCT) imaging. Chromatic aberration, optical
resolution, and detector array resolution are the key design consideration for high-quality OCT spectrometer.
Traditionally refractive optics spectrometer is used in SD-OCT. In the present work, the optical design of the reflective
optics spectrometer and of the refractive optics spectrometers is reported for high-speed line field optical coherence
tomography imaging. The performance of the spectrometers was compared by using the ZEMAX optical design
software. The ZEMAX optical modeling analysis shows that the reflective optics spectrometer provides better
performance by comparison with the refractive optics spectrometer.
Accurate characterization of doped semiconductors with terahertz spectroscopy
Author(s):
Osman S. Ahmed;
Mohamed A. Swillam;
Mohamed H. Bakr;
Xun Li
Show Abstract
The Characterization of the material optical properties with terahertz time domain spectroscopy is usually formulated
as an optimization problem with an objective function representing the deviation of the theoretical scattering parameters
from the measured ones. Both the magnitude and phase of the scattering parameters are utilized.
For samples of unknown thickness, false estimation of the thickness limits the accuracy of the results. We propose an
accurate optimization technique that predicts the actual thickness by solving only one optimization problem. Our
technique is also efficient compared to other techniques that solve N expensive optimization problems. Dispersive
dielectric models are embedded for accurate parameter extraction of a sample with unknown thickness.
For doped semiconductors we utilize the surface Plasmon Polariton behavior for accurately estimating the doping
level of semiconductor sample of unknown characteristics. By estimating the frequency at which the negative
permittivity exists, we can accurately estimate the doping level of the semiconductor. Our technique has been
demonstrated to be efficient and accurate through a number of examples.
Athermal silicon subwavelength grating waveguides
Author(s):
M. Ibrahim;
J. H. Schmid;
P. Cheben;
J. Lapointe;
S. Janz;
P. J. Bock;
A. Densmore;
B. Lamontagne;
R. Ma;
D.-X. Xu;
W. N. Ye
Show Abstract
In this paper, athermal subwavelength grating (SWG) waveguides are investigated. Both numerical simulations and
experimental results show that a temperature independent behaviour can be achieved by combining two materials with
opposite thermo-optic coefficients within the waveguide. SU-8 polymer with a negative thermo-optic coefficient (dn/dT
= -1.1x10-4 K-1) is used in our silicon SWG waveguides to compensate for silicon's positive thermo-optic coefficient of
1.9x10-4 K-1. The grating duty ratio required to achieve an athermal behavior is reported to vary as a function of the
operating wavelength and the waveguide dimensions. For example, for athermal waveguides of 260 nm in height, duty
ratios of 61.3% and 83.3% were calculated for TE and TM polarized light respectively for a 450 nm wide waveguide,
compared to ratios of 79% and 90% for a 350 nm wide waveguide. It is also reported that with increasing width, and
increasing height, a smaller grating duty ratio is necessary to achieve an athermal behaviour. A smaller fraction of silicon
would hence be needed to compensate for the polymer's negative thermo-optic effect in the waveguide core.
Subwavelength sidewall grating (SWSG) waveguides are also proposed here as alternatives to high duty ratio SWG
waveguides that are required for guiding TM polarized light. Assuming a duty ratio of 50%, the width of the narrow
segments for temperature-independent behavior is found by numerical simulations to be 125 nm and 143 nm for TE and
TM polarized light, respectively.
1x3 power splitter based on 2D slab photonic crystal multiple line defect waveguides
Author(s):
Rajat Dey;
Jayshri Sabarinathan
Show Abstract
2-D slab photonic crystal multiple line defect waveguides have been designed for optical power splitting
application which has numerous applications in photonic integrated circuit. The operation of the device is
based on multimode interference effects and self-imaging phenomenon. The proposed structure consists of
multiple photonic crystal line defect waveguides which are formed in the Γ-K direction by removing several
entire rows of air-holes. The adjacent photonic crystal waveguides are separated by a row of air-holes. In this
scheme a 1×3 power splitter is designed which involves three photonic crystal line defect waveguides
multimode region, five photonic crystal line defect waveguides multimode region and one separation region.
The entire structure is verified by 3-D finite difference time domain method. The transmitted power achieved
at each output channel i.e. CH1, CH2 and CH3 are about 26.3%, 26.8% and 26.3% respectively. The total
transmitted output power of 1×3 power splitter is 79.4% at target wavelength of 1.55μm.
Innovative architecture of switching device for expanding the applications in fiber to the home (FTTH)
Author(s):
Mohamed Mahmoud;
Heba A. Fayed;
Moustafa H. Aly;
A. K. Aboul Seoud
Show Abstract
A new device, optical cross add drop multiplexer (OXADM), is proposed and analyzed. It uses the combination concept
of optical add drop multiplexer (OADM) and optical cross connect (OXC). It enables a wavelength switch while
implementing add and drop functions simultaneously. So, it expands the applications in fiber to the home (FTTH) and
optical core networks. A very high isolation crosstalk level (~ 60 dB) is achieved. Also, a bidirectional OXADM and
N×N OXADM are proposed. Finally, a multistage OXADM is presented making some sort of wavelength buffering. To
make these devices operate more efficient, tunable fiber Bragg gratings (TFBGs) switches are used to control the
operation mechanism.
Asymmetric modified optical cross add drop multiplexer to eliminate crosstalk
Author(s):
Mohamed Mahmoud;
Heba A. Fayed;
Moustafa H. Aly;
A. K. Aboul Seoud
Show Abstract
A proposed new design of optical cross add drop multiplexer (OXADM) is presented. It reduces the number of required
circulators and total insertion losses compared with other circulator and FBG based designs. This enhances the isolation
and crosstalk levels. In the new design, the homodyne crosstalk is eliminated in the drop signal. Also, the homodyne
crosstalk in the output signal is reduced by more than 30 dB.
Simulation of PDMS microcantilever deflection using integrated optical fibers
Author(s):
Amir Sanati Nezhad;
Mahmoud Ghanbari;
Carlos Gustavo Agudelo;
Muthu Packirisamy;
Rama Bhat
Show Abstract
In this paper, a fully integrated flow sensor is designed and simulated. The sensor involves three PDMS layers,
monolithic integration of microfluidic channels and detection unit. The middle thin layer includes the PDMS
microcantilever and the microchannels network. The thin layer is sandwiched between the bottom and top PDMS layers
to provide microfluidic environment and to release the cantilever for deflecting. The pressure difference on the cantilever
causes the cantilever deflection. The optical fibers are embedded in the optical channels to send the light to the gold
deposited cantilever tip and to detect the reflected light. Finite element analysis is done using COMSOL Multiphysics
3.5. Fluid structure interaction is done on the cantilever to find the cantilever defection in response to fluid flow in the
microchannels. Optical power loss due to cantilever deflection is simulated by two integrated optical fibers. The
numerical results confirm the feasibility of detecting the PDMS cantilever deflection in the range of regular microfluidic
fluid flows.
Relation between sodium addition and excess selenium in Bridgman-grown CuInSe2
Author(s):
H. F. Myers;
C. H Champness;
I. Shih
Show Abstract
Ingots containing cm-sized monocrystals of CuInSe2 have been grown in quartz ampoules by a vertical-Bridgman
method. Included also in the ampoules were varying quantities of elemental Na, as well as excess Se above
stoichiometry. Deposits were seen within the ampoules after growth, including a white deposit formed through a
reaction of the Na with the quartz, and a reddish-brown deposit mostly containing Na and Se. Thermoelectric power
measurements indicate that stoichiometric material grown with no excess Se and no Na is p-type. With the addition of
Na above a critical amount to the ampoule, the resulting ingots were always n-type. This p to n conductivity type change
is inhibited when excess Se is also present, and more Na is required for the change to occur. The critical amount of Na
was found to be approximately twice the atomic amount of excess Se. XRD indicated that the chalcopyrite structure of
the material was maintained with additions of up to 3 at. % Na, even as the material was changed from p- to n-type, and
no sodium was detected in the bulk. It is suggested that a reaction between the Na and the Se occurs, resulting in the
formation of Na2Se. The Se used in this reaction is therefore unable to be a part of the CuInSe2 lattice, thereby
increasing the number of donor-like Se vacancies, rendering it n-type. In this model, the addition of excess Se replaces
those Se atoms which react with the Na, so that the material remains p-type.
Growth of large crystalline CuInSe2 ingots
Author(s):
Julia Qiu;
Andy Shih;
Yi Fan Qi;
Sunyoung Park;
Zetian Mi;
Ishiang Shih
Show Abstract
In previous Bridgman growth of CuInSe2 ingots, weighted amounts of high purity materials are introduced together into
quartz ampoules. During the initial heating, vigorous reaction occurs mainly between In and Se leading to a sudden
increase in the temperature and hence the vapor pressure. Explosion often occurs when the total amount of materials
exceeds 10 grams even with quartz ampoules with a wall thickness greater than 1 mm. Although the explosion can be
avoided by having very slow initial heating rate, the total materials are still limited to 30 g or less for each growth run.
Due to the limited materials, the dimensions of ingots grown in the previous experiments have been limited. In the
present work, we have developed a method to control the reaction between Se and In in the initial heating stage and
hence to reduce the rate of heat release in the exothermic reaction. Using this improved method, the limit on the material
amounts can be increased. Crystalline ingots with a total weight of 300 g and diameter 3 cm have been grown.
Surface relief diffraction gratings for plasmonic photocurrent enhancements in P3HT-PCBM solar cells
Author(s):
Ribal Georges Sabat;
Marcos Jose Leite Santos;
Paul Rochon
Show Abstract
A 260 nm layer of organic bulk heterojunction blend of the polymer poly (3-hexylthiophene) (P3HT) and the
fullerene [6,6]-phenyl C61-butyric (PCBM) was spin-coated in between aluminum and gold electrodes
respectively on top of a laser inscribed azo polymer surface relief diffraction grating. Angle dependent surface
plasmons (SP) with a large band gap were observed in the normalized photocurrent by the P3HT-PCBM layer
as a function of wavelength. The highest increase in photocurrent was found to be 272% at a wavelength of
618 nm for a grating depth of 50 nm. The SP-induced photocurrents were also investigated as a function of
the grating depth and spacing.
Low density of gold nanorods in the anodic layer for enhancing the efficiency of organic solar cells
Author(s):
Alaa Y. Mahmoud;
Jianming Zhang;
Jayanta K. Baral;
Ricardo Izquierdo;
Dongling Ma;
Muthukuraman Packirisamy;
Vo-Van Truong
Show Abstract
The effect of using an anodic layer with low density (~ 6x108 cm-2) of gold nanorods (GNR) in organic bulk
heterojunction poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) solar cells was studied.
GNRs were deposited using several techniques, which produced various densities of GNRs on the anode layer. The
anodic layers were characterized microscopically and spectroscopically. The power conversion efficiency and the short-circuit
current for experimental devices incorporating GNR anodic layer showed an enhancement of up to 18% as
compared to the control device. The results suggest that the electric field in the P3HT:PCBM active layer was increased
by the localized surface plasmon resonances in GNRs. The increase in the electric field enhanced the photo-generation of
excitons in the active layer near the plasmon peak, which improved the short-circuit current and the overall power
conversion efficiency. Interestingly, photovoltaic devices with a low density of GNRs in the anodic layer showed an
increase in the power conversion efficiency that was superior to that of devices with a higher density of GNRs in the
anodic layer. This suggests that although the anodic layer with a higher density of GNRs absorbed more light, part of this
light was confined in the anodic layer itself, and prevented from reaching the active layer of the bulk heterojunction
device. In such cases, the power conversion efficiency was even found to be decreased with respect to the value for the
control device.
Modeling of the electrical carrier transport in III-V on silicon tandem solar cell structures
Author(s):
T. K. Maiti;
Dan Cheong;
Jingfeng Yang;
R. N Kleiman
Show Abstract
The electrical carrier transport of a tandem cell structure was evaluated by investigating the band alignment of
and carrier transport through a tunnel junction. The modeling structure of a tandem cell consists of a III-V (or
II-VI) top cell layer, a Si bottom cell layer and tunnel junction layers in-between which connect the top and
the bottom cells. The values of energy bandgap and electron affinity of each layer were varied to investigate
their effect on the energy barrier height at the interface between Si and compound semiconductors of interest.
The contour plots of barrier heights for majority and minority carriers at the hetero-interface are used as a
starting point to define the successful regions for electrical carrier transport through the tunnel junctions.
Metal contacts to p-type crystalline CuInSe2
Author(s):
Sunyoung Park;
Clifford H. Champness;
Zetian Mi;
Ishiang Shih
Show Abstract
Bilayers of metal contacts were deposited on p-type monocrystalline copper indium diselenide (CuInSe2) and the
resistance between two contacts were measured to find low resistance metal contacts on crystalline CuInSe2. The first
metal layer was Ni, Pt, Se, or Te and the second metal layer was Au, Ag, Al or Cu. It was observed that the resistance
reduced when the surface of crystalline CuInSe2 were etched before metal deposition with a solution containing H2SO4(1 %, w/w) and CrO3 (1 %, w/w). It was confirmed that the resistance increases after heat-treatments at high temperature.
The stability of the metal contacts in room air was estimated from the resistance measured for a period of over 20 days.
Thermal modelling of laser processing for silicon photovoltaics
Author(s):
Christopher Baldus-Jeursen;
Siva Sivoththaman
Show Abstract
Laser bending of ductile materials is a promising manufacturing method for industry because it is contact free, and
without spring-back effect. Although laser bending of metals (stainless steel, titanium, aluminum) has been explored
since the early 1980's, laser bending of brittle materials such as silicon, borosilicate glass, and ceramics, is a relatively
new field of research. Deformed silicon structures find application in microchips (clip chips, MEMS), and silicon
cantilevers for atomic force microscopes. In the field of photovoltaics, silicon laser bending allows for novel cell
architectures. The subject of this paper is the experimental investigations of laser bending of silicon combined with
simulation techniques to model the temperature field.
Charge carrier mobility in conjugated organic polymers: simulation of an electron mobility in a carbazole-benzothiadiazole-based polymer
Author(s):
Yaping Li;
Jolanta B. Lagowski
Show Abstract
Inorganic (mostly silicon based) solar cells are important devices that are used to solve the world energy and
environmental needs. Now days, organic solar cells are attracting considerable attention in the field of
photovoltaic cells because of their low cost and processing flexibility. Often conjugated polymers are used in the
construction of the organic solar cells. We study the conjugated polymers' charge transport using computational
approach that involves the use of the density functional theory (DFT), semiempirical (ZINDO), and Monte Carlo
(MC) theoretical methods in order to determine their transfer integrals, reorganization energies, transfer rates
(with the use of Marcus-Hush equation) and mobilities. We employ the experimentally determined three
dimensional (3D) structure of poly(9,9'-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) to estimate the electron
mobility in a similar co-alternating polymer consisting of carbazole and benzothiadiazole units (C8BT). In
agreement with our previous work, we found that including an orientational disorder in the crystal reduces the
electron mobility in C8BT. We hope that the proposed computational approach can be used to predict charge
mobility in organic materials that are used in solar cells.
Lowest surface recombination velocity on n-type crystalline silicon using PECVD a-Si:H/SiNx bi-layer passivation
Author(s):
Dmitri S. Stepanov;
Zahidur R. Chowdhury;
Nazir P. Kherani
Show Abstract
Energy conversion efficiency of crystalline silicon (c-Si) solar cells manufactured on thin substrates is strongly
influenced by the recombination losses of photo-generated charge carriers at the surface and in its proximity. Intrinsic
hydrogenated amorphous silicon (i-a-Si:H) deposited using DC saddle-field plasma enhanced chemical vapour
deposition (PECVD) at a low temperature of ~200°C reduces recombination losses of photo-generated carriers through
passivation of defects at the surface. This study reports on high quality surface passivation achieved using a dual layer
approach wherein a 70nm amorphous silicon nitride (SiNx) capping layer is deposited on a less than 10nm thin i-a-Si:H
layer. While the a-Si:H layer is effective in passivating the interface recombination sites, SiNx is deemed to incorporate
field-effect passivation, thus providing a minority carrier mirror. Additionally, SiNx layer acts as an anti-reflection
coating with a low absorption coefficient in the optical frequency range of interest. The SiNx deposition conditions,
known to strongly influence the passivating quality of the dual layer structure, were systematically investigated using the
response surface methodology (RSM). The optimal deposition parameters obtained from the RSM study were
experimentally verified to yield the lowest surface recombination velocity of 3.5 cm/s on 1-2 Ω-cm n-type FZ c-Si using
a PECVD a-Si:H/SiNx bi-layer passivation stack.
Fe doped TiO2 nanofibers on the surface of graphene sheets for photovoltaics applications
Author(s):
Nasrin Farhangi;
Yaocihuatl Medina-Gonzalez;
Paul A. Charpentier
Show Abstract
Highly ordered, visible light driven TiO2 nanowire arrays doped with Fe photocatalysts were grown on the surface of
functionalized graphene sheets (FGSs) using a sol-gel method with titanium isopropoxide (TIP) monomer, acetic acid
(HAc) as the polycondensation agent and iron chloride in the green solvent, supercritical carbon dioxide (scCO2). The
morphology of the synthesized materials was studied by SEM and TEM, which showed uniform formation of Fe doped
TiO2 nanofibers on the surface of graphene sheets, which acted as a template for nanowire growth through surface
-COOH functionalities. Increasing Fe content in the nanowires did not change the morphology significantly. Optical
properties of the synthesized composites were examined by UV spectroscopy which showed a significant reduction in
band gap with increasing Fe content, i.e. 2.25 eV at 0.6% Fe. The enhancement of the optical properties of synthesized
materials was confirmed by photocurrent measurement. The optimum sample containing 0.6% Fe doped TiO2 on the
graphene sheets increased the power conversation efficiency by 6-fold in comparison to TiO2 alone.
Thermal optimization of a solar cell carrier for concentrator systems
Author(s):
Aaron Muron;
Simon Chow;
Jeffrey Wheeldon;
Karin Hinzer;
Henry Schriemer
Show Abstract
Solar cell efficiency decreases as its temperature increases. Therefore, it is necessary to design a thermally optimal solar
cell carrier that will maintain a minimal solar cell temperature. To achieve this optimal solar cell carrier design, a finite-element
analysis model of the solar cell on carrier was developed. This numerical model was experimentally calibrated
against a known design, in which the average solar cell temperature was determined by examining the shift in the open
circuit voltage. This allowed us to explore the relationship between the carrier geometry and the average solar cell
temperature. That is, the solar cell carrier is characterized by two independent thermal resistances: the uniform flow
thermal resistance, and the thermal spreading resistance. As the copper thickness was increased, the uniform flow
resistance acted to raise the cell temperature while the spreading thermal resistance decreased the cell temperature.
Therefore, when the carrier geometry minimized the thermal resistances, it was found that the minimum solar cell
temperature was achieved at a copper thickness between 1.5 and 3 mm depending on the surface area of the carrier. This
optimized carrier design reduced the average solar cell temperature by 16 °C, which corresponds to an increase of 0.8%
in cell efficiency at 1666 suns as compared to the original design used to experimentally calibrate the numerical model.
Synthesis and properties of zinc oxide nanowires for photovoltaics
Author(s):
Bita Janfeshan;
Siva Sivoththaman
Show Abstract
Zinc oxide is a wide band gap semiconductor with a large exciton binding energy (60meV). As a result the
nanostructures of this material have many potential applications in electronic and optoelectronic devices. In this work,
the growth and optical properties of ZnO nanowires have been studied. The nanowires (NW) of ZnO were synthesized
using low pressure chemical vapour deposition method (LPCVD) under different chamber pressures. The growth was
carried out on (100) Si wafers pre-coated by gold particles as a catalyst. The morphology of the synthesized NWs and
their optical properties like transparency and reflection were studied. The NW arrays have high optical transmittance
compared to ZnO thin films prepared by sputtering. The photoluminescence of the NWs were also measured and
compared with that of ZnO thin films. The two types of NW structures obtained have potential applications in
photovoltaic devices as optical and electrical components.
Spatial and spectral non-uniform irradiance distribution effects on multijunction solar cells
Author(s):
M. Victoria;
R. Herrero;
C. Domínguez;
I. Antón;
S. Askins;
G. Sala
Show Abstract
When refractive optical systems are used to concentrate light onto high efficiency solar cells chromatic aberration creates
irradiance distributions over the cells which are neither spatially nor spectrally uniform. Multijunction solar cells are the
photovoltaic device with the highest conversion efficiency. However, their efficiency under a concentration system can
be significantly lower than the measured efficiency under uniform irradiance and reference conditions. In this paper the
irradiance distribution created by a Fresnel lens is studied by ray-tracing simulations and it is characterized using a CCD
camera and adequate filters. The effects of the non uniform irradiance distribution on the solar cell performance are
analyzed by measuring the IV curve of an elementary unit of the system when illuminated by a solar simulator. IV
curves for different lens to cell distances are measured and compared to allow a better understanding of the system.
Design of a multiplexer to characterize individual optics at a concentrating photovoltaic test site
Author(s):
Matthew Wilkins;
Richard Beal;
Joan E. Haysom;
Jeffrey F. Wheeldon;
Philippe Mulet;
Graeme Jamieson;
Nashed Youssef;
Dhan Balachandreswaran;
Jennifer Fan;
Trevor Hall;
Stefan Myrskog;
Karin Hinzer
Show Abstract
An on-sun Concentrating Photovoltaic (CPV) test site with a multiplexed current-voltage measurement capability has
been installed at the University of Ottawa. Herein, we present details of the instrumentation, which is designed to
provide in-situ I-V measurements of individual solar cells within a functioning, series connected, string. A 4-wire
multiplexing system enables current-voltage measurements of individual cells. Where other multi-cell test systems have
left cells at open-circuit or connected to a fixed resistor when not selected by the multiplexer, in this system each test
cell operates within a string of cells controlled by a maximum power point tracker. This allows us to maintain the test
cells at realistic operating conditions for all irradiance conditions. Using the current-voltage data, a range of parameters
of interest can be monitored over time, including the solar cell temperature, photovoltaic efficiency and optical
efficiency. This information is correlated with time-synchronized spectrometer and pyrheliometer data, allowing
automated collection of performance data from several strings of optic/solar cell assemblies. The test site includes two
20m2, dual-axis, ring mounted solar trackers and is being used to test new CPV systems which incorporate novel lightguiding
optics designed and manufactured by Morgan Solar Inc.
Building integrated semi-transparent photovoltaics: energy and daylighting performance
Author(s):
Konstantinos Kapsis;
Andreas K. Athienitis
Show Abstract
This paper focuses on modeling and evaluation of semi-transparent photovoltaic technologies integrated into a coolingdominated
office building façade by employing the concept of three-section façade. An energy simulation model is
developed, using building simulation software, to investigate the effect of semi-transparent photovoltaic transmittance
on the energy performance of an office in a typical office building in Montreal. The analysis is performed for five major
façade orientations and two façade configurations. Using semi-transparent photovoltaic integrated into the office façade,
electricity savings of up to 53.1% can be achieved compared to a typical office equipped with double glazing with
Argon filling and a low emissivity coating, and lighting controlled based on occupancy and daylight levels.e.c
Design of a metal-dielectric subwavelength slit structure for high efficiency coupling of surface plasmon polaritons
Author(s):
Reyad Mehfuz;
Kenneth J. Chau
Show Abstract
We propose a high efficiency coupling scheme of surface plasmon polaritons (SPP) in a metal-dielectric slit structure. The design includes a narrrow silver-slit structure, which is immersed in a dielectric with refractive index 1.5. We map the dependence of SPP coupling efficiency on the dielectric layer thickness (d). By varying d the dispersion behavior of the SPP mode is tuned enabling minimized wavevector mismatch between the light exiting the slit and the SPP mode. A dielectric layer of thickness in the range 50 nm < d < 150 nm yields coupling efficiencies of approximately 80%, representing a nearly four-fold enhancement relative to the coupling efficiency without a dielectric layer.