This PDF file contains the front matter associated with SPIE Proceedings Volume 7278, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing

This paper reports recent development and application of optical fiber gas sensors using absorption spectroscopy, including open-path gas sensors using fiber coupled micro-optic cells and photonic bandgap (PBG) fibers. A fiber-optic sensor system capable of detecting dissolved fault gases in oil-insulated equipment in power industry is presented. The gases include methane (CH₄), acetylene (C₂H₂) and ethylene (C₂H₄). In addition, the development of gas sensor using PBG fiber will be reported.

A new design for tuning optical fiber grating is proposed. The fiber grating is placed in the grooves between a pair of slides, in which one end of the fiber is bonded on the bottom slide, and the other end of the fiber is bonded on the top slide, the grating section of the fiber is confined in grooves, so that the fiber grating is remaining straight without buckling during axial compressive force applied to the fiber. An actuator is used for driving slide to apply force on fiber to axially compress or stretch the fiber grating. The wavelength of the fiber grating is tuned according to applied stress on the fiber. The applications of the device include tunable fiber laser, tunable fiber filter etc.

In this paper, the recent progresses in the optical code division multiple access (OCDMA) technology for the future optical access networks are reviewed including OCDMA/WDM system configuration, en/decoding devices, OCDMA prototype, and demonstrations.

40Gb/s high-speed communication system has many advantages and could be widely used in future. But there are also many factors affecting this system; especially PMD is one of the most important factors. In this paper, we focus on analyzing the influence of PMD. With analyzing the reasons which caused PMD, we improved Fiber Spinning Unit (FSU) and developed spinning process independently. Through spinning fiber in a sinusoidal way, controlling the amplitude and frequency of the spinning wheels, we dramatically reduced the value of PMD (≤0.03 ps - km^-1/2). Finally, we tested the value of PMD in different situations, such as PMD of single plate fiber, PMD in optical fiber link and PMD in simulative optical cable. The results indicated that PMD can be strongly reduced by spinning fiber while drawing and the fiber links could also have lower PMD. So fibers with low PMD can be well used by different network operators with good effect in return.

Widely tunable laser diodes are key components for agile optical networks and optical sensing systems. In this paper, a monolithic widely tunable sampled grating distributed Bragg reflector (SGDBR) laser diode was fabricated using LPMOCVD. Butt-joint technique was adopted to realize lateral integration of MQW active area and passive waveguide. The etching process and MOCVD regrowth were well optimized to obtain ultra low loss butt coupling and improve the reproducibility. The coupling loss of butt-joint waveguide is as low as 7cm^-1. The fabricated SGDBR laser used a typical ridge waveguide (RWG) structure due to the advantage of the simple fabrication processing. It was consisted of four sections, two "sampled grating" passive reflectors (front mirror and rear mirror), MQW gain section, and phase section. This SGDBR laser diode had 26mA threshold current and 9mW maximum output power at 100-mA continuous-wave operation. Through control of the injection current of front mirror and rear mirror, the spectra with the tuning range of more than 41nm was obtained. And the wavelength can be precise aligned at ITU wavelength by well adjustment of the phase section injection current. The side mode suppression ratio in the whole tuning range was more than 30dB.

We have designed a high nolinear photonic crystal fiber by considering nonlinear coefficient, chromatic dispersion and confinement loss. The detail of the design process is presented in this paper. According the simulation results, we have fabricated a kind of highly nonlinear photonic crystal fiber, which is characteristics with the flatten dispersion curve at 800nm wave band and negative dispersion at wavelength of 805nm (about -40ps/nm/km). In this kind of PCF we design the zero dispersion around 800nm. With the fabricated fiber, we demonstrate that supercontinuum emission with spectrum stretching over 900nm is obtained by injecting Ti: sapphire laser pulses.

This paper holds landslide monitoring system based on fiber optic sensors network. When structural distortion is occurred in landslide area, it will affect the change of fiber bragg grating space, and brings on the offset of the fiber bragg wavelength.The information of the destroyed point is obtained with the demodulated system.It applies annular distribution to mountain body, and establishs homologous fiber optic sensor network which collect all the information to the home site. This technique can provide the managers, policy-makers and experts the real time change of the parameters of the disaster, and the feedback can be given to monitoring station through the monitoring network. Therefore, it will be an important technical support for real time dynamic monitoring.

Fiber Bragg gratings were inscribed in two types of grapefruit microstructured fibers with 193 nm excimer laser and phase mask method. The response of fiber Bragg gratings to strain, temperature and hydrostatic pressure were characterized. The air holes enhance the response to pressure.

A method based on FBG sensor array to monitoring large structure's security state is described. A configuration combing a fiber Fabry-Perot tunable filter and a fiber Fabry-Perot interferometer is used to interrogate FBG sensors. The strain signal and acceleration signal can be obtained from the some one FBG sensor, and the number of DFB sensors is reduced to half. The fiber Fabry-Perot tunable filter-based system has the capability to interrogate large number of DFB sensors, whilst obtaining absolute Bragg wavelength with pm resolution. A demonstration system with 4 DFB sensors is presented, which obtains DFB sensor's direct strain value and achieves sub-microstrain resolution at 300Hz interrogating rate. With fast interrogate rate, wide band acceleration signal can also be achieved.

The disadvantage of the symmetric signal demodulating method for DFB laser hydrophone is showed. Because of the different transmission coefficients of the three signal channels, the symmetric condition is dissatisfied. A model with three unsymmetrical interferometric signals is simulated. The simulated result shows that the output signal's amplitude is modulated. In order to correct the unsymmetrical coefficients, PGC (phase generated carrier) technique is introduced to the signal demodulating scheme. The experimental result shows that the PGC technique can improve the signal's symmetry and the output signal's amplitude-modulated problem does not appear obviously.

Gain guided and index antiguided fiber, having a negative refractive index step from the cladding to the core combined with an adequate gain effect, can deliver robust single mode operation with a large mode area. In this paper, we introduce this new concept of gain guided and index antiguided fiber into fiber amplifier, and evaluate the gain characteristics by solving propagation rate equations on the Yb3+ doped fiber, where the core has a radius of 50um, refractive index n₀ = 1.58, and the index step Δn = -0.0045, concentration of ions 2.43×10²⁶m^-3, at the signal (975nm) and the pump (910nm) wavelength and a initial signal power 1μW. According to the function of gain versus fiber length, being obtained from the numerical computation, we can confirm that a properly designed gain guided and index antiguided fiber can provide highly efficient optical amplification with a short length, and revise the set of transcendental equations at optimal total gain effect and optimal fiber length on the case of gain guided and index antiguided fibers.

During the construction and service period of concrete bridges, the cracks often influence the quality of the project even the safety of the structure. An effective and long-term crack monitoring of concrete bridges with the appropriate choice of displacement sensors is imperative under the situation. The differential fiber bragg grating displacement cell is based on the composite structure which consisted of pulling spring and cantilever. It has realized differential measure of normal FBG displacement sensor and has solved the serious problem of temperature disturbance. The differential fiber bragg grating displacement cell has the advantages of high accuracy, anti-interference, long distance transmitting and good durability etc. In this paper, the differential fiber bragg grating displacement cells were applied to monitor the cracks of web slabs during the tension process of external prestressed tendons when the continuous prestressed concrete box girder bridges and continuous concrete rigid frame bridges were maintained and reinforced. A group of typical cracks of web slabs was selected respectively in the continuous prestressed concrete box girder bridge and the continuous concrete rigid frame bridge. And a group of three sensors were installed across the three cracks. The external prestressed tendons had been tensioned by four grades. Then the widths of these cracks were recorded in accordance with the four tension grades of the external prestressed tendons: before tension, 10% tension, 80% tension, 100% tension. The results of the differential FBG displacement cells used during the process of tension of external prestressed tendons show that the cracks monitoring data are accurate and in accordance with the cracks changing rule.

Propagation characteristics of the femto-second chirped soliton pulse in dispersion-flatted fiber with linear dispersion profile (DFF-LDP) are numerically investigated by using the split-step Fourier method (SSFM), and variations of its characteristics affected by high-order dispersion (β2~β6), Raman effect, fiber loss and linear chirp parameter C are studied. A new type of DFF-LDP with negative dispersion slope is presented. The pulse broadens with the increase of propagation distance mainly because of fiber loss and third order dispersion (TOD). The effect of the positive chirp on pulse broadening is greater than that of the negative chirp. The time-delay induced by TOD and Raman effect appears, and decreases with increase of the chirp |C|. The main body of the pulse spectrum shifts to the long-wavelength region, an obvious separated spectrum appears in the short-wavelength region. The separated spectrum for the chirped case is more obvious than that for the unchirped case.

As a new-type sensing element, fiber grating has gained abroad attention from its appearance and achieved high-speed development in the last 20 years. With the development of fiber grating technology, study on the application of Fiber Bragg Grating (FBG) sensor has got more recognition. In this paper the fiber grating sensing system consists of four parts: light-source, fiber grating sensor, demodulation circuit and signal process circuit. The properties of FBG, the demodulation technology of the sensor, and the network technology are studied experimentally and theoretically. The following are the main contents: (1) The sensing characteristics of FBG are analyzed, with the result of a linear relationship between the central wavelength of FBG and the temperature strain. Meanwhile, the temperature and strain sensing experiment results agree with the theoretical analysis. (2) The demodulation method of fiber grating is the key technology of fiber grating sensor. The main demodulation method includes: filtering method, interference method, tunable light source scanning method. We can use anyone of them to detect FBG's central wavelength. (3) The demodulation method based on tunable light source is used, and a fiber grating sensor system based on this method is developed. Tuning the light source until its output matches the central wavelength of FBG, the peak value will display, and then the temperature or strain could be known according to this wavelength.

In the paper,The research progress of current sensor was introduced.And the working principle,characteristics and disadvantages were analyzed.We explore optical current sensor based on Fiber Loop Ring Down Spectroscopy (FLRDS), The sensing system consists of a fiber sensor head and a typical fiber loop ring down system including a pulsed VCSEL laser diode at 850 nm,multimode fiber couplers,multimode fiber loop,photo-receiver and high-speed data acquisition and signal processing. The current sensor is demonstrated with a resolution of 0.05 A ,the sensor system's good linear responses,stability,repeatablity,sensitivity are also explored.

Based on EPS technology, multiple π-EPSs have been employed in the design of the OCDMA en/decoders. It has been shown that the cross-correlation will be enhanced under the same parameters. And also this method demonstrates a method to extend the code capacity.

Tunable filters with a wide tunable rang have been found wide applications and be the key component in fiber optical communication system and fiber sensor system. It is hard to fabricate a fiber Fabry-Perot tunable filter. In this paper, the principles of Fabry-Perot filter is introduced, and a novel tunable Fabry-Perot filter is designed and fabricated. The fabricated process of the tunable filter is described and the transmission spectrum of tunable F-P filter in experiment is given and discussed. The tunable F-P filter has the advantages of simple structure, low modulated voltage and cost effectiveness. The filter can be applied to wavelength interrogation in fiber Bragg grating (FBG) sensing system to detect the drift of the fiber Bragg wavelength.

A two-wavelength fiber laser with two π-equivalent phase shifts (EPSs) is studied and fabricated. The π-EPS is obtained through extending one sampling period by 50% in a fiber sampled Bragg grating (SBG). To get a two-wavelength fiber laser lasing in the -1st channel, two π-EPSs are introduced in the position of L/3 and 2L/3 in the SBG, where L is the total length of the SBG. A stable 22-pm-spaced dual wavelength DFB fiber laser is achieved in the experiment.

A novel scheme of gas concentration detection based on a frequency modulation technique is introduced in this paper, which resolves the problems of centric wavelength drift and variations of modulation amplitude by using an ASE source, FBG and a specific mechanical vibration device. A wavelength Scanning optical source for gas detection can be easily achieved.

Now, most favors fiber access is mainly the EPON fiber access system. Inheriting from the low cost of Ethernet, usability and bandwidth of optical network, EPON technology is one of the best technologies in fiber access and is adopted by the carriers all over the world widely. According to the scheme analysis to FTTH fan-end equipment, hardware design of ONU is proposed in this paper. The FTTH far-end equipment software design deference modulation design concept, it divides the software designment into 5 function modules: the module of low-layer driver, the module of system management, the module of master/slave communication, and the module of main/Standby switch and the module of command line. The software flow of the host computer is also analyzed. Finally, test is made for Ethernet service performance of FTTH far-end equipment, E1 service performance and the optical path protection switching, and so on. The results of test indicates that all the items are accordance with technical request of far-end ONU equipment and possess good quality and fully reach the requirement of telecommunication level equipment. The far-end equipment of FTTH divides into several parts based on the function: the control module, the exchange module, the UNI interface module, the ONU module, the EPON interface module, the network management debugging module, the voice processing module, the circuit simulation module, the CATV module. In the downstream direction, under the protect condition, we design 2 optical modules. The system can set one group optical module working and another group optical module closure when it is initialized. When the optical fiber line is cut off, the LOS warning comes out. It will cause MUX to replace another group optical module, simultaneously will reset module 3701/3711 and will make it again test the distance, and will give the plug board MPC850 report through the GPIO port. During normal mode, the downstream optical signal is transformed into the electrical signal by the optical module. In the upstream direction, the upstream Ethernet data is retransmitted through the exchange chip BCM5380 to the GMII/MII in module 3701/3711, and then is transmitted to EPON port. The 2MB data are transformed the Ethernet data packet in the plug board TDM, then it's transmitted to the interface MII of the module 3701/3711. The software design of FTTH far-end equipment compiles with modulation design concept. According to the system realization duty, the software is divided into 5 function modules: low-level driver module, system management module, master/slave communication module, the man/Standby switch module and the command line module. The FTTH far-end equipment test, is mainly the Ethernet service performance test, E1 service performance test and the optical path protection switching test and so on the key specification test.

Factors influencing the birefringence property of double cladding fiber (DCF) are numerically investigated for DCF with rectangular and D-shape inner cladding. Research shows that the choices of inner cladding shape, outer cladding material and cooling temperature have considerable influence on thermal induced birefringence in the core of DCF. Birefringence increases with the increase of Young's Modulus, thermal expansion coefficient, thickness of outer cladding, and the ellipticity of inner cladding.

The article describes the theory, characters and performance of the linear array of photodetectors includes CCD, PDA, CMOS and InGaAs, presents fiber grating sensor demodulation technique using linear InGaAs array and designs the demodulation system based on this technique. Furthermore, the system is used to measure the strain and temperature respectively, and prove the system have a good practicability. The demodulation system has a high resolution and measurement precision, changes the size of traditional Fiber Grating Sensors demodulation system essentially, and realizes basically the intelligence of the FBG sensors and lays a foundation for the industrialization of the FBG sensors.

Bridge engineering offer many unique opportunities for the use of advanced optical fiber sensing technology. In this paper, the state-of-the-art of bridge structural health monitoring system(SHMS) based on optical fiber sensing technology are reviewed and some disadvantages in present SHMS based on optical fiber sensing technology for existing long-span bridge are indicated. In order to overcome those disadvantages, some fiber Bragg grating (FBG) products developed by authors and corresponding industrialization enterprise are introduced. Focusing on an existing long-span cable-stayed bridge-Wuhan Yangtze No.2 Bridge, the operational condition of the multi-parameter bridge SHMS mainly based on FBG sensors is presented. Some initial monitoring results show that the whole performance of the SHMS FBGbased is reliable and measuring data are reasonable.

With the development of optical fiber manufacture and optical fiber sensor technology, more and more attention is paid to the photonic crystal fiber (PCF) sensors, such as gas sensors, bend sensors and strain sensors. Especially, the bend character of PCF is very important for designing bend sensors. In this paper, we adopt the multipole method to study the bend character of Total Internal Reflection PCF (TIR-PCF), and the relationship between bend radius and bend loss of TIR-PCF is investigated theoretically. As a result, the bend loss of PCF will be variable according to bend radius and it is also different with the same bend radius as the TIR-PCF structure parameter is different. Furthermore, the bend stress distribution on the TIR-PCF is analyzed carefully, and the minimum endurable bend radius is given. The simulation result in this paper will provide primary references for the PCF bend sensors designing.

In this paper, by using ethyl silicate, ethanol and fluorescence indicator as the precursors, the multifunctional optic biosensing (MOBS) film containing cholesterol oxidase and the fluorescence indicator was prepared by sol-gel method. This biosensing film has both the function of biocatalyst and oxygen biosensing and can be used as the effective biosensing materials for fiber optic cholesterol sensor. The fiber optical cholesterol sensor based on fluorescence quenching was designed and fabricated using lock-in amplifying technology to realize the detection of cholesterol concentration. The experimental results showed that the best precursor proportion in volume ratio is: ethyl silicate: ethanol: 0.01 M HCl = 5: 8: 1.6. The drying rate of the sol could be controlled by using formamide as the controlling drier. When 16% of formamide were added in the mixing system, the cracks of the film could be reduced greatly and the immobilization of cholesterol oxidase and the fluorescence indicator could be improved effectively. A linear relationship between phase delay φ and the cholesterol concentration was observed in the range of 100 to 500 mg/dL. Since the cholesterol concentration is in the range of 140 to 200 mg/dL in the blood of healthy people, it will be possible for the sensor to be used in clinical detection. The biosensor with MOBS film has the response time of about 30 s, which is rather fast for a biosensor, and the relative deviation of ±5.03%. This biosensor also has good stability.

The advantages of Optical Packet Switching (OPS) are transparent data transmission and data format, flexible packet control and dynamic resource allocation. It thus can support high-speed transmission of wideband data networks. Unlike Optical Burst Switching (OBS) systems which need reserved channel to transmit destination address, an advanced OPS solution using Optical Orthogonal Code (OOC) label for payload transfer has been proposed in this paper. Different from other OPS systems, our edge nodes are required to realize some special tasks including extracting destination addresses of the received IP packet which is used as payload in our OPS systems and sending the addresses to the OOC label generator. The OOC label will later be used to identify the destination of each payload at the core node for optical switching. Meanwhile, the higher-priority flow can be prior-serviced according to the Type of Service (TOS) in the head of IP packet. It is experimentally shown that the edge nodes in this OPS system can effectively improve the efficiency of packet switching and the speed of data transmission. The edge node implementation contains two parts: the hardware and software. For the hardware part, all necessary modules have been integrated onto one PCB board, thus avoiding possible instability caused by interconnecting different modules like transmitting/receiving Ethernet frame module, Field Programmable Gate Array (FPGA) processing module and optical transceiver module etc. from different Printed Circuit Boards (PCB). For the software part, the whole of system was based on MicroC/OS-II operating systems running on the Nios II soft core processor. It is verified by the experiment that embedded system designed with Nios II soft core CPU can help to speed up the hardware design. With the SOPC Builder's development environment, more attention can be paid to the structure and function of the system without worrying about the details of the circuit design, and better performance on system stability and reliability could be achieved at the same time.

In this paper an efficient method is proposed to maximize the tuning range of a fiber parametric wavelength converter based on degenerated four-wave mixing. The physical mechanism behind efficient phase matching over a broad wavelength range has been analyzed as a function of the fiber dispersion and nonlinear properties. Analytic expressions of the optimum input signal wavelength and maximal bandwidth are deduced and it is revealed that by carefully selecting fibers with appropriate zero dispersion wavelength and high-order dispersion coefficients the tuning range can be greatly broadened and tailored to cover any WDM bands.

A novel dual chirped fiber Bragg gratings (CFBG) accelerometer is proposed in this paper. The method with CFBG instead of FBG has two advantages. One is that the matching relation of the dual CFBG can be easily realized, while the other is that the linear measurement range is larger than that with FBG. The CFBG accelerometer with elastic system composed of a mass block and a steel tube shows good performances such as higher resonate frequency, larger linear measurement range, easily to fabricate, lower cost, and so on. The sensor with a resonance frequency of 3812Hz has a larger measurement range from 0.1g up to 10g.

A light absorption sensor is based on phenomena of light absorption between in two flow stream layers with different refractive index in liquid/liquid (L²) waveguide in this letter. The diffusion between the core and the cladding forms the tapered L² waveguide sensor. The taper can be controlled by the flow rates of the core and the cladding layers. The absorption sensor is fabricated using PDMS onto a microfluidic chip, which chip size is 3.5cm × 3cm and the absorption length is 2cm. Two different aqueous dye solutions such as rhodamin 6G and methylene blue are measured and approved by the experimental results of the absorption sensor. The limitation of detection is 0.5ng/mL for rhodamin 6G and 0.16ng/mL for methylene blue. The L² waveguide absorption sensor has high potential usage for the biological, chemical and medical measurement applications.

Fiber Bragg Grating (FBG) is a basic component in optical communications and optical sensing of strain or pressure or temperature. In this paper, a novel geophone based on FBG is designed and used in the system of nuclear explosion seismic wave detection. The detection principle is analyzed and the mechanical model is established. According to the characteristics of the nuclear explosion seismic wave and the demands of the detection system, the parameters of the novel FBG geophone are calculated, and the results show that the sensitivity coefficient is 0.54pm/ms^-2 and the work frequency bands are 0~653Hz and 2830~3266Hz. The prototype detection system is devised and tested through the simulation seismic wave. The experiment indicates that, compared with the traditional electronic sensors, the system has higher sensitivity and stability, the start time of the seismic wave arrived the detection position can be surveyed accurately. Combined with the nuclear explosion detecting sub-system based on the radiation, the distance between the bomb location and the detector can be calculated accurately.

This paper reports an ameliorative technique for distributed fiber optics sensing based on Brillouin optical time-domain reflectometry (BOTDR) and Brillouin optical-fiber time-domain analysis (BOTDA). Because the electro-optic modulator in BOTDR system has a finite extinction ratio, the pulsed laser always contains a CW component, which is hereafter called leakage. The frequency of the leakage is p_v which is the same as that of the pulse, and the frequency of the Stokes wave is s_v. The frequency of the acoustic wave b_v at each point along the fiber matches the beat frequency of the leakage and the Stokes wave. As a result, when given an appropriate extinction ratio, the leakage will have a biggish effect on the Stokes wave, which is the same as the function between the continuous wave and the Stokes in BOTDA system. The Stokes component in spontaneous Brillouin scattering (SPBS) is amplified by the leakage along the distance when it backs to the laser end, which is the well known stimulated Brillouin scattering (SBS) phenomena. So long as the distance from the point where the SPBS engender to the laser end is long, the intensity of the SBS signal is relatively large owing to the longer amplified interval. In BOTDR system, when setting the extinction ratio at 20dB, using the SBS signal we can achieve a SNR which is approximately 5 dB greater than that of traditional system and the dynamic range performance 3 dB greater. Utilizing this new technique in BOTDR system it also has an ascendency compared with BOTDA system in respect that it access to only one end of the fiber with probe pulse light.

Two interleavers with potential applications for dense wavelength division multiplexing (DWDM) system are designed based on the analysis of the phase characteristic of Gires-Tournois resonator. One has only one G-T resonator and the other has two. The performance of the two interleavers has been compared .We find the latter is better than the former and an Interleaver of a channel spacing of 50GHz, ripple less than 0.05dB, a -0.5dB passband of 23.4GHz (46.8% of the spacing), a-30dB stopband of 20.8GHz (41.6% of the spacing), and a channel isolation of -33.95dB is obtained.

We propose a scheme of BB84 quantum key distribution (QKD) with a triggered parametric down-conversion (PDC) source. According to different results of Alice's measurement using a photon number resolving (PNR) detector, we separate photon pulses into three sets to implement the passive decoy method. Performances of two different kinds of widely-used PNR detectors, TES and TMD, are investigated by simulation. With the parameters of PNR detectors nowadays, TES and TMD perform similarly. Both of them can improve the secure transmission distance up to 171 km. Furthermore, compared with the case using threshold detectors, this scheme can achieve a higher key generation rate.

Optical Orthogonal Frequency Division Multiplexing (OOFDM) is a novel optical signal transmission technology, which can access to high performance in existing fiber channel especially the Multi-Mode Fiber channel. This paper shows a numerical simulation of the transmission performance of Adaptively Modulated Optical Orthogonal Frequency Division Multiplexing (AMOOFDM) system in MMF and SMF channel with Adaptive Cyclic Prefix (ACP), using directly modulated DFB lasers and Intensity-Modulation and Direct-Detection (IMDD). According to the modulation format based on channel estimation and Adaptive Cyclic Prefix, it is shown that 12.5Gbps over 1km in typical MMF channel and 12.5Gbps over 500km in SMF channel are feasible.

A maximum-likelihood sequence estimation (MLSE) based equalizer with Viterbi algorithm is designed in this paper. It can effectively compensate the intersymbol interference (ISI) caused by the polarization mode dispersion (PMD).The simulation results prove that the electronic equalizer, in 40Gbit/s non-return-to-zero (NRZ) optical system with Gaussian noise, can mitigate the polarization mode dispersion (PMD) and improve performance of the communication system. At the last, we compared the MLSE equalizers and DFE(FFE),we can come to the conclusion that the MLSE equalizer is the best way to combat polarization mode dispersion(PMD) and it can improve performance of system effectly.

Processing and experiment of an Optical Orthogonal Codes (OOC)-based all-optical label for Optical Packets Switching (OPS) using Fiber Bragg Grating (FBG)-based encoder/decoders is reported in this paper. The Print Circuit Board (PCB) with Filed Programmable Gate Array (FPGA) is designed to produce high speed single pulse and configure the optical switching system to choice the OOC-based labels. The FBG-based encoder/decoders are designed. The results show that the experiment of OOC-based optical labels and configure of the optical switching system by using FPGA is performed successfully.

A novel configuration of fiber-optic liquid-level sensor based on an extrinsic Fabry-Perot cavity is presented and demonstrated in this paper. The main principle of this sensor is that output intensity will vary linearly in a locally special linear region with liquid-level increasing and cavity length decreasing. The experimental results prove that the actual curve of extrinsic Fabry-Perot cavity is approximate cosine curve, and that the peak values of the fringes slowly decrease with increased cavity length. Consequently, cavity length loss influences on performance indexes of extrinsic Fabry-Perot cavity optical fiber sensors operating in linear region such as measurement range, sensitivity, minimum resolution, and linearity. To obtain high finesse and throughout for reducing the complexity of signal processing system, the loss must be kept as small as possible by selecting an appropriate cavity length in view of different sensing surface and reflectivity. Otherwise, the sensor with too small initial cavity length can output more intensity, perform wider range of measurands, possess higher minimum resolution, and is more sensitive, but the linearity becomes worse and the measurement errors are maybe unavoidable to rise. On the contrary, with bigger original cavity length, the things are opposite. Hence, the original cavity length and the end reflectivity must be selected appropriately to meet with the requirements for performance indexes of the liquid-level sensor in realistic circumstance.

This paper proposes a proactive contention avoidance mechanism through dedicated wavelength assignment method in the optical burst switching network. In our scheme, one or more dedicate wavelengths are assigned to each ingress node and each ingress node transmits incoming bursts to various destination with its dedicated wavelength. Therefore contention at intermediate core nodes can be avoided and contention is localized at each ingress node, in where this situation can be resolved by means of electric buffer. Furthermore, based on the status of traffic distribution, we propose a constructive scheme to construct a load-balanced spanning tree for each ingress node, where input loads are balanced appropriately among each output port of ingress node. And, identical wavelength can be shared with bursts transmitted to different destination nodes within the spanning tree. Thus our scheme has statistical multiplex gain and it expected to utilize wavelength effectively. Simulation result indicates the burst loss performance can be improved drastically without wavelength conversion comparing with those algorithms that completely shared wavelength link.

In an optical packet switching (OPS) system, the label processing is crucial for OPS, since the optical label carries the switching and routing information of optical packets. This paper introduces the scheme and the principle of the Optical Orthogonal Code (OOC)-based optical labels for OPS networks, and points out the importance of optical label processing with inconsecutive, random and bursting characters. Considering these of optical labels, we designed a circuit consisted with widening net and cascading multi-level amplifiers to receive single tiny narrow pulse of optical labels, the experiments results indicate the designed scheme is effective.

We propose a novel scheme for generation and detection of a 40 Gb/s binary frequency shift keying (FSK) signal. Multispan transmission properties are numerically compared with return-to-zero (RZ) and differential phase shift keying (DPSK) formats. Experimental demonstration shows that a 40 Gb/s FSK signal is transmitted over 50 km standard single-mode fiber (SMF) with 0.8 dB penalty and over 12 dB resilience of span input power, clearly validating the feasibility of this FSK modulation scheme. Transparent wavelength conversion for a 43Gb/s RZ-FSK signal is successfully achieved by FWM in a SOA and in HNDSF. 2R regeneration is also to be purposefully observed in HNDSF which results in limited over-all penalty after 100km transmission link.

In this paper, the injection locking technique is investigated by applying the external lightwaves to a Fabry-Perot laser (FP-LD). The static and dynamic characteristics are studied in detail, which include optical spectrum analysis such as the output intensity, the side mode suppression ratio (SMSR), and the mode selection characters, as well as the dynamic linewidth suppression, the wavelength detuning speciality, and the frequency responses. With proper adjustments, the maximum SMSR of 50 dB is obtained, and the frequency response of the injection-locked FP-LD has been improved with the proper wavelength detuning. Besides, we concentrate on the applications of the injection locked FP-LD in wavelength-division-multiplexing passive optical network (WDM-PON) systems, and a protection scheme for WDMPON transmitters spare function is proposed and demonstrated at the same time. Compared with the conventional methods, this proposed architecture provides a cost-effective and reliable protection scheme employing a common FPLD. In the experiment, a 1:36 protection capability was implemented, in the wavelength range from 1537.4 nm to 1565.4 nm.

The polarization-maintaining fiber coupler (PMFC) is a kind of optical coupler manufactured with polarization-maintaining fiber (PMF). It is the pivotal device to realizing the linearly polarized light coupling, the dispersion of light as well as the multiplying. It is one of the core components of the high-precision fiber optic gyroscope (FOG) and fiber optic hydrophone. This paper reports a kind of thin-diameter PMFC (cladding diameter is 80μm), which is developed to adapt to the FOG's miniaturization. The difference between the thin-diameter PMFC (Φ80μm) and conventional PMFC (Φ125μm) in the manufacture technology has been compared. The key technologies of developing the thin-diameter PMFC (Φ80μm), such as "No tension fused taper", "On-line adjusting main axes of the PMF", "High stability package" and so on, has been discussed. In addition, it also has been carried on some Mechanical and environmental tests. The test results show that the thin-diameter PMFC can satisfy the requirements of the miniature FOG.

During last years, interest in pulsed magnetic field sensors has widely increased. In fact, magnetic field measurement has a critical part in various scientific and technical areas. In order to research on pulsed magnetic field characteristic and corresponding measuring and defending means, a sensor with high immunity to electrical noise, high sensitivity, high accuracy and wide dynamic range is needed. The conventional magnetic field measurement system currently use active metallic probes which can disturb the measuring magnetic field and make sensor very sensitive to electromagnetic noise. Photonic magnetic field sensor exhibit great advantages with respect to the electronic ones: a very good galvanic insulation, high sensitivity and very wide bandwidth. Photonic sensing technology is fit for demand of a measure pulsed magnetic field. A type of pulsed magnetic field photonic sensor has been designed, analyzed, and tested. The cross polarization angle in photonic sensor effect on the signal-to-optical-noise ratio is theoretically analyzed in this paper. A novel approach for improving the signal-to-optical-noise ratio of pulsed magnetic field sensors was proposed. The experiments have proved that this approach is practical. The theoretical analysis and simulation results show that the signal-to-optical-noise ratio can potentially be considerably improved by setup suitable for the cross polarization angle.

A novel metal-coated fiber Bragg grating (MFBG) pressure sensor based on the thin-wall strain cylinder with temperature compensation was designed and fabricated. According to the elastic strain principle, the theoretical analysis of the strain distribution of this structure was described by calculation and simulation software Ansys. A sensing MFBG1 was soldered on the tangential direction on the exterior surface of the thin-wall strain cylinder, and another MFBG2 was soldered on the axial direction to compensate the effect of temperature. The experimental results indicated that the cross-sensitivity of pressure and temperature of this sensor can be self-compensated well by this method. In addition, the actual measurement pressure range from 0 to 42 MPa with a high pressure sensitivity coefficient of 0.0496 nm/MPa. Simultaneously, the measure range of pressure can be adjusted by changing the structure material and the geometry size of the sensor. This kind of sensor has potential applications in the sensing measurement at harsh environment.

This paper presents a novel method of measuring acceleration based on the special D-shaped fiber Bragg grating(DFBG). The accelerometer has several features: small size and light weight, simple structure, and detecting both very low frequency (on the order of 0.1 Hz) and small acceleration (1.15 ×10-3g). The sensitivity of the accelerometer reaches 563.67με/g.

With the continued rapid growth of Internet, new network service emerges in endless stream, especially the increase of network game, meeting TV, video on demand, etc. The bandwidth requirement increase continuously. Network technique, optical device technical development is swift and violent. FTTH supports all present and future service with enormous bandwidth, including traditional telecommunication service, traditional data service and traditional TV service, and the future digital TV and VOD. With huge bandwidth of FTTH, it wins the final solution of broadband network, becomes the final goal of development of optical access network. Firstly, it introduces the main service which FTTH supports, main analysis key technology such as FTTH system composition way, topological structure, multiplexing, optical cable and device. It focus two kinds of realization methods - PON, P2P technology. Then it proposed that the solution of FTTH can support comprehensive access (service such as broadband data, voice, video and narrowband private line). Finally, it shows the engineering application for FTTH in the district and building. It brings enormous economic benefits and social benefit.

With the rapid development of digital networks, many of the appliances in life are widely used, particularly in wireless LAN and IP telephony. Ethernet-based data terminals have been widely used in many areas, although the device's power consumption is low, but in general stability and reliability of the power is of very high requirements. In this paper, PoE technology (a solution focused on long-distance power supply system) is focused on the PoE power supply equipment, power-operation process, the system configuration management, automatic detection, and other major technology. Also, at the same time it introduces the use of PoE technology for wireless access points designed to supply power as a kind of typical application in the local network, the programme through the network to provide power system solutions, and expand the use of PoE equipment and make full use of the existing network resources, providing users with convenient and stable service.

Based on digitization, multimedia, mobility, wide band, real-time interaction and so on,family networks, because can provide diverse and personalized synthesis service in information, correspondence work, entertainment, education and health care and so on, are more and more paid attention by the market. The family network product development has become the focus of the related industry. In this paper,the concept of the family network and the overall reference model of the family network are introduced firstly.Then the core techniques and the correspondence standard related with the family network are proposed.The key analysis is made for the function of family gateway, the function module of the software,the key technologies to client side software architecture and the trend of development of the family network entertainment seeing and hearing service and so on. Product present situation of the family gateway and the future trend of development, application solution of the digital family service are introduced. The development of the family network product bringing about the digital family network industry is introduced finally.It causes the development of software industries,such as communication industry,electrical appliances industry, computer and game and so on.It also causes the development of estate industry.

Radio-over-Fiber networks providing millimeter-waveband (mm-waveband) signals using wavelength-divisionmultiplexing techniques are foreseen as the next paradigm to provide broadband wireless access services.Millimeter wave band operating RoF provides high bandwidth due to its high frequency feature, so it is perfectly adapted to these system. But a limited cell range with propagation losses leads to frequent handovers when hopping from one remote antenna units to another causes numerous packet losses strongly, thus to reduce the whole system bandwidth. Moving cells concept is introduced for avoiding the classical handover time. Nevertheless, frequent switching in optical switches is inevitable in the resolution which also result in dropping calls. Therefore, a concept of cells extension to allievate the burden of handover in contral station is proposed. However, since the adjacent RAUs employ the same channel in an extensive larger cell, co-channel interference exists in the extension scheme. To avoid this, a time slot distributor in the star-tree architecture of RoF network to support the moving cell extension is proposed and a MAC protocol is designed for this concept to avoid the co-channel interference.

A fiber optic wide region temperature sensing system based on optical pulse correlation measurement and SHG differential detection technique is proposed and demonstrated. In order to establish the reliability of this fiber optic temperature sensing system, a long-term wide region outside temperature monitoring experiment with a new designed 20ps time-bias optical pulse correlation unit for wide measurement rang was carried out. The temperature measured by means of a correlation sensor had the same variation as and higher sensitivity and quick measurement response than the digital thermometer. The resolution of the correlation sensor is approximately ±0.01 ^oC . This fiber optic temperature sensor can measure even in very tough environment and low and high temperature range. Not only point temperature but also a field area average temperature can monitor by this system.

With the development of sensor techniques, low-power and inexpensive wireless sensors have been put into application, then the wireless sensor networks have appeared. Wireless sensor networks can be applied to many areas and have become a new research focus. Many applications of wireless sensor networks are based on sensor self-positioning, which depend on knowing the location of sensor nodes. So the location techniques of sensor nodes are being important. In this article, the principles and characteristics of wireless networks are discussed and presented. The taxonomy for wireless sensor networks localization systems is described. The principles and characteristics of some representative range-free localization approaches are also discussed. The article focuses on the investigation of DV-Hop location algorithm after contrast it with other range-free algorithms. DV-Hop localization uses a mechanism that is similar to classical distance vector routing which uses the product of hops and hopsize to represent the distance. We use VC++ to simulate this algorithm and point out matters needed attention. After got the simulation results, we analyze the result at length, and focus at nodes density and other factors which influence location accuracy, and the reason of the effect is discussed in detail.

A novel method to realize the adjustable phase-shifted fiber Bragg grating (FBG) is proposed in this paper. By adjusting the air gap between two identical FBG, the phase shift has been changed, and the transmission characteristics of such phase-shifted FBG can be tuned. Both theoretical simulation and experimental measurement have been carried out to verify and demonstrate the idea. It has been shown the proposed tuning method is effective and the experimental results agree well with the theoretical prediction.

An experimental research on the wavelength conversion utilizing non-degenerate four-wave mixing in photonic crystal fiber is presented. Two pumps and a 25 m dispersion flattened and highly nonlinear photonic crystal fiber are used in our non-degenerate four-wave mixing experimental study. The wavelength conversion bandwidth is about 65 nm. The wavelength conversion efficiency is -22.7 dB when the powers of two pumps are 17.3 dBm and 13.4 dBm. The conversion efficiency in the wavelength range of 1 530 to 1 560 nm is stable.

As video on demand (VOD) services are deployed, cable operators will experience a fundamental shift in their business, moving from broadcast to unicast content delivery. Another significant change is the introduction of Gigabit Ethernet into their network, which is providing an unprecedented opportunity to turn the cable operator's infrastructure into a sustainable competitive advantage. However, Gigabit Ethernet is more than just transport; it's the foundation of the Next-Generation Digital Video Network. IPQAM modulator, which is a main equipment, aren't made in China so far. It is the first time that we did design IPQAM modulator and will apply it to interactive TV based on DWDM (dense wavelength-division multiplexing). This paper introduces the principle of IPQAM modulator and transmission approach. The differences between IPQAM and conventional QAM are analysed. Some key techniques such as scrambling, statistical multiplexing, Data over Cable Service Interface Specification (DOCSIS) 3.0, software defined radio as well as DVB simulcrypt are also studied.

Finite-Difference Time-Domain(FDTD) method and Finite-Difference Frequency-Domain(FDFD) method are widely used to analyze transmission characteristics of many transmission systems. Based on 2-D FDFD method, general analysis formulas for the circular ridged waveguide are derived. The proposed method is effective for almost ridge structures, if the boundary condition changed accordingly. To confirm this method, a number of numerical results are achieved and compared with others using different methods. Good agreements are gained, which demonstrates the accuracy of 2-D FDFD method. Also the method is not time-consuming, which indicate the efficiency.

High power 980nm pump lasers are the key components in optical fiber amplifier. Wavelength stability for 980nm Miniuncooled pump laser is required to maintain the amplifier's efficiency throughout its lifetime. In this paper, a new type of wavelength stabilizer for uncooled pump laser which utilizes two fiber Bragg gratings (FBGs) matched in wavelength, bandwidth, and reflectivity is presented. The characteristics of transmissivity and reflectivity for the dual FBGs stabilized 980nm pump laser are theoretically modeled and experimentally studied. The results show that the output spectral characteristics of the uncooled pump laser with the dual FBGs have been greatly improved. The laser module can work steadily over a wide temperature range from 0°C to 70°C, with 0.2nm wavelength shift, along with more than 45dB side mode suppression ratio, and less than 1.57nm spectral bandwidth.

The single sideband (SSB) modulation format is obtained using the narrowband fiber Bragg grating (NFBG) made by ourselves. Then The SSB modulation format and double sideband (DSB) modulation format transmit over 155 km G.652, respectively. And dispersion is compensated by chirp fiber Bragg grating (CFBG) made by us. The results show that the power penalty of SSB signal is smaller than that of DSB signal when the input power and the bit error rate (BER) are the same; when the BER is E-12, the power penalty of SSB signal is 0.8 dB smaller than that of DSB signal.

A polarization maintaining fiber (PMF) magnetic field sensor based on a digital phase generated carrier (PGC) technology is presented. A magnetic sensor constructed with two magnetostrictive strips attached on the sensing fiber is joined in the sensing arm of a fiber Michelson interferometer. The fiber optic interferometric system is made of all PMF, which inhibits the polarization-induced signal fading. The light source is a fiber laser which can be modulated directly. The PGC metnod is used to demodulate magnetic field signal avoiding phase induced interferometric signal fading, and ensure the sensing partto be all fiber structure. A fiber optic magnetic field sensor with appreciate size for the fiber optic hydrophone towed array is obtained, which can be used to sense the enviromental magnetic field along the sensing direction.This sensor is a good choice for the directional angle measurement through sensing the Earth magnetic field in the array shape measurement of a fiber optic hydrophone towed array.

As an effective alternative to the nature enzyme, metallophthalocyanine (MPc), having the advantages of easy accessibility, good stability and low cost, are used as catalyzer for the adrenaline (AD) oxidation. In this paper, the oxidation of AD by dioxygen using iron(II) phthalocyanine (FePc) as the catalyst was studied by electronic absorption spectra. The experimental results indicate that the oxidation product of AD catalyzed by FePc is adrenochrome with characteristic peaks at 298 nm and 267 nm. The catalytic activities of FePc are evaluated by the ratios of the absorbance at 298 nm of adrenochrome. The optimal concentration, pH and temperature for the oxidation of AD are 5.0×10^-5 M, 8.0 and 55 ^oC, respectively. By using lock-in technology, the fiber optic adrenaline biosensor based on FePc catalysis and fluorescence quenching was fabricated and studied. A linear relationship between φ, the phase delay of the sensor head, and AD concentration was observed in the range of 2.0×10^-6 to 9.0×10^-6 M and 2.0×10^-5 to 9.0×10^-5 M. The standard deviation (SD) values are 4.7×10^-8 (n = 5) and 5.9×10^-7 (n = 5) M, respectively, while the detection limit is 4.0×10^-7 M. The biosensor has the response time of about 15 min and the preferred reproducibility and stability.

An improved token bucket algorithm (Improved TB) is introduced for the Dynamic Bandwidth Allocation (DBA) in an Ethernet Passive Optical Network (EPON). The scheme is simple and of low computational complexity, it can guarantee both the efficiency and fairness of the DBA. Simulation results using synthetic traffic confirm its good performance against existing bandwidth allocation scheme.

It is very important for the photonic crystal fiber character to monitor its properties synchronously during the fabrication process so that a series of draw parameters can be efficiently optimized as PCF used to be produced. In this paper, we reported an efficient method to monitor PCF properties with the cross-section of the photonic crystal fiber collected by microscope and CCD. The structure parameters of the cross-section of PCF are fast picked up by digital process technology and the properties of the PCF produced are efficiently analyzed by a finite element method. The method is very helpful in optimizing the draw parameters and improving the properties of PCF.

The properties of long period gratings in Photonic crystal fibers (PCFLPGs) are systematically analyzed by the improved full-vector effective index model and the coupled mode theory. Dual-resonance peak occurs in PCFLPGs. The dependence of the strength of coupling and the resonance wavelength on the hole pitch, the relative hole size, the grating period, the length of grating, the refractive index modulation depth and the chirp coefficient is studied. Some useful conclusions are obtained, which provide the theoretical basis for the applications of PCFLPGs such as the optical fiber communication, the optical fiber sensing and so on.

Fibre Channel (FC)becomes the main storage protocol of SAN(Storage Area Network).Enterprises are increasingly deploying FC-SANs in their data central. In order to mitigate the risk of losing data, more and more enterprises are increasingly adopting storage extension technologies based on WDM (Wavelength Division Multiplexing) to replicate their business critical data to a secondary site. Storage Extension based on WDM makes use of the flow control mechanism based on Credit, it offers immediate access to the full link bandwidth without a ramp-up time ,but the updating frequency of Credits and the throughput of storage extension are limited by the long extension distances. Adding the receiver memory can remove those limitations, but it also brings about the long queuing time. In this paper, a Petri-Net model of FC flow control protocol is constructed to analysis the relative degree between the storage extension performance with bandwidth, distance and initial number of Credit. Meanwhile, a new integrative flow control mechanism for storage extension based on WDM is proposed, it is consists of three flow control loop A,B and C. A is deployed between FC sender and WDM ingress gateway, B takes affection on the WDM ingress gateway and WDM engress gateway, C works among WDM engress gateway and FC receiver, and the three flow control loop are integrated by the buffer utilization of ingress and engress gateway. Theoretical analysis and simulation result show that the new flow control method can effectively remove distance limitation and allow data traffic to flow at maximum throughput without adding queuing latency. The new flow control method is implemented in WDM gateway, it is transparent for FC protocol and can provide a good compatibility.

Glycerol with high concentration can enhance optical clearing of skin by injecting into derma, but previous investigations also found that it may block the blood once glycerol acted on small vessels. This work aims to explore the safety of glycerol as an optical clearing agent of skin. Here, 0.05ml of 75%, 50%, 40%, 30%, 20% glycerol solutions and saline were injected into the dorsal dermas of SD rat, respectively. To compare the optical clearing effect, the diffuse reflectance spectra were monitored just immediately, 2h and 24h after the injection of solutions. In order to investigate the long term effect of glycerol on the local skin, the photos at the interest area were taken. The results showed that the high concentration solutions (40%, 50%, 75% glycerol) made local skin necroses badly which was irreversible in 2 weeks. The low concentration solutions (20% glycerol) could cause neither skin damage nor optical clearing effect. 30% glycerol could reduce the reflectance spectra of skin by 20% without injury. Therefore, 30% glycerol is an available agent for skin optical clearing through injection treatment.

In this article, a novel instance is introduced in optical-fiber white light interferometer experiment. In the experiment of measurement the thickness of a piece of glass by optical-fiber white light interferometer, five while not one interference signal were found. The wrong result could be concluded because of more interference signal come out in the measurement of optical fiber sensor technique based on the white-light interferometer.

A new scheme is proposed to control the gain spectrum of semiconductor optical amplifiers (SOA). Carrier distribution along cavity is changed by non-uniform current injection in a multi-electrode SOA. Based on the multi-section model, the gain bandwidth characteristics of a two-electrode SOA are analyzed. The possibility of controlling the gain spectrum of SOA by multi-electrode pumping is shown.

A tunable wavelength conversion of coherent signals light based on the four-wave mixing (FWM) in the photonic crystal fiber (PCF) is demonstrated in this paper. The phase match condition of four-wave mixing in photonic crystal fiber has been discussed, and the wavelength range that satisfies the phase match condition has been summarized. By use of 20- meter photonic crystal fiber whose zero dispersion wavelength is at about 1550 nm and whose nonlinear coefficient at 1550 nm is ~11 (Wkm)^-1, tunable wavelength conversion is achieved. The measured maximum conversion efficiency of 1554.42 nm and 1537.3 nm coherent signals light is -15 dB and -7 dB respectively, and the 3dB conversion bandwidth is over ~50nm.