We review and contrast key technologies developed to address the optical components market for telecom applications. We first look at different material systems, compare their properties, and describe the functions achieved to date in each of them. The material systems reviewed include silica fiber, silica on silicon, silicon on insulator, silicon oxynitride, sol-gels, polymers, thin film dielectrics, lithium niobate, indium phosphide, gallium arsenide, magneto-optic materials, and birefringent crystals. We then look at the most commonly used classes of technology and present their pros & cons as well as the functions achieved to date in each. The technologies reviewed include passive, actuation, and active technologies. The passive technologies described include fused fibers, dispersion-compensating fiber, beam steering (e.g., AWG), Bragg gratings, diffraction gratings, holographic elements, thin film filters, photonic crystals, microrings, and birefringent elements. The actuation technologies include thermo-optics, electro-optics, acousto-optics, magneto-optics, liquid crystals, total internal reflection technologies (e.g., bubble technology), and mechanical actuation (e.g., moving fibers, MEMS). We finally describe active technologies including heterostructures, quantum wells, rare earth doping, Raman amplification, and semiconductor amplification. We also investigate the use of different material systems and technologies to achieve building block functions including lasers, amplifiers, detectors, modulators, polarization controllers, couplers, filters, switches, attenuators, non-reciprocal elements for isolators and circulators, wavelength converters, chromatic dispersion compensators, and polarization mode dispersion (PMD) compensators. Some of the technologies presented are established in the industry, others have recently been proven to be commercially viable, and some others are still under development in laboratories.

We discuss an application of nonlinear characteristics of optical fiber gratings. A cascaded long-period fiber grating pair shows a very sharp interference fringe patterns in wavelength domain. This can be applied to the modulation of optical beam intensity by the use of cross-phase modulation. The core mode can be switched to the cladding mode by the method, and the pulse intensity needed in the switching is reduced by an order of magnitude compared to the previous method. We also discuss bidirectional wavelength add/drop multiplexers (B-WADM's) using fiber Bragg gratings (FBG's) and multi-port optical circulators. A further modification of this structure that uses two separate multiplexer (MUX) and demultiplexer (DEMUX) pairs and reflection-type FBG filters is also discussed. The proposed B-WADM alleviates the formerly stringent requirement on MUX/DEMUX crosstalk characteristics, while suppressing the power penalty induced by the Rayleigh backscattering or optical reflection. In experiment, the measured crosstalk induced by the backscattering was successfully suppressed to negligible level (-30 dB) while at the same time achieving high B-WADM span gain over 25 dB.

Increasing demands on the high capacity wavelength division multiplexed (WDM) transmission system now require newly developed transmission windows beyond the gain bandwidth supported by erbium-doped fiber amplifiers (EDFA). With the intensive development efforts on new rare-earth dopants and fiber nonlinearity (Raman process) for fast few years, wideband optical amplifiers now can support easily over 4-5 fold wider gain bandwidth than it was formerly possible with the conventional EDFAs. Of various breeds for this application, there exist three distinct approaches near 150nm band, accessible in the commercial market. These include: Thulium-doped fluoride fiber amplifiers (TDFA) for S+band (1450-1480 nm) and S band (1480-1530 nm), EDFAs for C band (1530-1560nm) and L band (1570-1610nm) and L band (1570-1610nm), Raman amplifiers with 100 nm's of gain bandwidth (with flexible location from S+ to L Band), and hybrid amplifiers with serial/parallel combinations of above techniques. Even though there have been much increased experimental reports for all of these amplifiers, the complexity of the amplification dynamics from the number of involving energy levels and difficulty in measuring experimental parameters make it harder than ever to predict the performance of wideband amplifiers in general. This lack of serious study on the analytic or numerical analysis on wideband amplifiers could cause the future impairments for the prediction and estimation of the amplifier performances for different applications, restricting the successful deployment of wideband amplifier based transmission systems. In this paper, we present the numerical model and analysis techniques for wideband amplifiers (C/L band EDFA, Raman amplifier, and TDFA),along with their application examples.

Significant improvements in technology have made phased array antennas an attractive alternative to the traditional dish antenna for use on wide body airplanes. These improvements have resulted in reduced size, reduced cost, reduced losses in the transmit and receive channels (simplifying the design), a significant extension in the bandwidth capability, and an increase in the functional capability. Flush mounting (thus reduced drag) and rapid beam switching are among the evolving desirable features of phased array antennas. Beam scanning of phased array antennas is limited to +/-45 degrees at best and therefore multiple phased array antennas would need to be used to insure instantaneous communications with any ground station (stations located at different geographical locations on the ground) and with other airborne stations. The exact number of phased array antennas and the specific installation location of each antenna on the wide body airplane would need to be determined by the specific communication requirements, but it is conceivable as many as five phased array antennas may need to be used to provide the required coverage. Control and switching of these antennas would need to be accomplished at a centralized location on the airplane and since these antennas would be at different locations on the airplane an efficient scheme of remoting would need to be used. To save in cost and keep the phased array antennas as small as possible the design of the phased array antennas would need to be kept simple. A dish antenna and a blade antenna (small size) could also be used to augment the system. Generating the RF signals at the central location and then using RF cables or waveguide to get the signal to any given antenna could result in significant RF losses. This paper will evaluate a number of remoting alternatives to keep the system design simple, reduce system cost, and utilize the functional capability of networking multiple phased array antennas on a wide body airplane. Included in these alternatives will be the use of optical modules as the true time delay in the phased array antennas and using a fiber optic bus from the centralized control to drive the optical modules.

An high-efficiency optical filter composed of counter-propagating wavelength converter in ZnTe, is demonstrated. The device has a extremely narrow bandwidth 0.5 angstrom, corresponding to pump intensity 1.2MW/cm² and length of crystal 1cm, is tunable over several nanometers in bandwidth using combination of length of device and pump intensity. The presented scheme is also a candidate of wavelength-dependant switcher.

The saturation effect of EDFA on frequency filtering characteristics of active fiber ring resonators is studied theoretically and experimentally in this paper. When input signal power is large enough, it would enter the saturation regime and lower EDFA gain, thus, the finesse of active fiber ring resonator descends as the same when lower pump power is injected, all of which are confirmed by comparing the output signal spectrums with different input signal power and different pump power in our experiments. By using the atom rate equations of EDFA and the multi-light interference theory, the experiment results are well explained. On considering this EDFA saturation effect, the optimization of active fiber ring resonator filter is also discussed. To obtain both narrower linewidth light and larger output power, one should use input coupler with small coupling ratio and output coupler with large coupling ratio to construct an active fiber ring resonator filter, making sure that saturation effect of EDFA can not occur.

This paper discusses an optical fiber acousto-optic phase modulator coated with piezoelectric ZnO. The geometry of optical fiber using ZnO coating has firstly been presented and the basic theory of piezoelectric resonator of this geometry been analyzed. Also, the equivalent network model for the optical fiber acousto-optic phase modulator coated with piezoelectric ZnO has been given. And then, the reflection coefficient R_f has been obtained by this model. Finally, calculation of R_f has been made in great detail according to the practical parameters.

This paper proposes and demonstrates a novel MEMS variable optical attenuator whose attenuation mechanism is completely different from those in literature. The basic operation principle is that the optical power coupled between two initially aligned single mode fibers will be continuously attenuated while the end of one of the fibers is deflected from the initial position. A micromachined solenoid type inductor with a U-shaped permalloy magnetic core is used to attract the deflectable fiber that has a permalloy coat on its end part. To fabricate the multi-layer three-dimensional inductive component, a new UV-LIGA lithography process for thick photoresists is developed combining advantages of both SU-8 and AZ-4000 photoresists. Micro electroplating techniques are also used to produce the copper coil and permalloy core. The inductive component is approximately 1.7mm x 1.3mm x 50μm large and has a low resistance value (2.1 Ω). The whole size of the VOA before packaging is 30mm x 2mm x 0.6mm. The first prototype shows less then 3-dB insertion loss at 0-dB attenuation and nearly 40dB attenuation range with less then 20mw electrical input power at 1550nm.

With the advent and applications of Generalized Multi-Protocol Label Switching (GMPLS: an optical extension to traditional Multi-Protocol Label Switching), today's optical networks evolve towards Intelligent Optical Network (ION). In this paper we firstly describes a novel IP-Centric optical network architecture called Hierarchical Optical Routing Switching Architecture (HORSA) based on GMPLS--a flexible, highly scalable IP over WDM optical network architecture for the delivery of public network IP services. Two kinds of node including Optical Core Router (OCR) and Optical Edge Router (OER) are involved in this optical network architecture. In this section we also discuss some issues such as routing, signaling and management of HORSA. Secondly, we mainly focus on the design issues of OCR and OER including multi-granularity switching fabrics, intelligent OTU, control plane software and etc. Finally, we reach conclusions that HORSA based on GMPLS is suitable for current hybrid network environment and optimistic for IP traffic transfer, it can be scaled to pure optical IP over WDM architecture based on Optical Packet Switch (OPS).

The basic technology of adaptive optical amplifier is introduced in this paper. How the performance of optical amplifier may meet the needs of application system is discussed according to the amplitude and shape of the input optical signal, the amplifier automatically adjusting the operating parameters. Taking the EDFA as an example, the feasibility to be realized technology of adaptive amplifier is investigated.

With the wide spread use of wavelength-division-multiplexing (WDM) technology to enlarge the capacity of existing communications networks, the cost of electronic processing equipment, such as SDH/SONET add-drop multiplexers (ADMs), IP routers, MPLS switches, has replaced the cost of optics as the dominant cost factor in network deployment. Traffic grooming studies the logical topology design problem in WDM networks where low-speed connection requests are groomed into lightpaths connecting nodes that may be physically apart. In this paper, we address traffic grooming in interconnected WDM bi-directional rings. We propose the use of a two-stage multiplexing scheme supporting dual-homing interconnection, which actually provides additional levels of grooming. We present a set of formal mathematical formulation of the whole problem. Optimal solution can be obtained from the formulation.

In current high performance IP Gigabit Switching Router (GSR) design, one of the key issues is about switching fabrics. In the traditional bus-based router architectures, the data transfer rate of copper backplanes will soon reach the speed limit because of connector reflections and crosstalk. An optical switching fabric technology is necessary in order to satisfy the demand for high bandwidth and line switching rate. In this paper we firstly present a novel all-optical broadcasting switch fabric design scheme based on broadcasting bus architecture. In this section we also discuss the advantages and disadvantages of this kind of architecture and demonstrate that this kind of switching fabric architecture have no interior blocking as well as none I/O blocking (e.g. HOL). Secondly, we discuss such implementation scheme of all-optical broadcasting switch fabric architecture as queuing, scheduling and multicasting. Finally we get a conclusion that all-optical broadcasting switch fabric is one of the cost-effective solutions to design high-speed, scalable and simple switch fabric compared with complicated electric crossbar switch fabrics in GSR design.

A new non-communication optical fiber--Multimode Tapered Optical Fiber (MTOF) is designed for Desktop Rapid Prototyping System(DRPS), which delivers much greater output energy than non-MTOF of the same output diameter. Its transmission ratio much increased. The DRPS' process is introduced, followed by the choose and design of MTOF, coupling and focusing of UV light. MTOF has some advantages, such as flexibility,low cost,high efficiency. The application of MTOF in DRPS that requires low cost will make concrete fundamental for populating the system.

We designed some important parameters and analyzed loss characteristics of a 8X8 polymer arrayed waveguide granting multuplexer that operates around the wavelength of 1.55 micrometers and the wavelength spacing was 16nm. The total loss of the device includes the diffraction loss in the input and output (I/O) slab waveguides, bent loss caused by the AWG and 1/O channels, and leakage loss resulted from the high refractive index substrate. The effects of some structural parameters on the loss characteristics are investigated and discussed. The computed results show that when we select the core thickness as 4 micrometers , core width as 6 micrometers , pitch of adjacent waveguides as 15.5 micrometers , diffraction order number as 50, the number of the arrayed waveguides as 91, that the I/O channels as 8,confined layer thickness between the core and the substrate as 6 micrometers , distance between the focal point and the origin as 5500 micrometers , and central angle between the central waveguide and the vertical of the symmetrical line of the device as 60 deg, then the total loss of the device can be dropped to about 3.73 dB.

This paper introduces a novel hierarchical model of optical transport network (OTN) and discusses the functional architecture of optical supervisory channel (OSC) with a Q-factor on-line supervision module which can provide a reliable evidence for the transmission quality of operation, administration and maintenance (OA&M) signals in the OSC subsystem of OTN. The quality indication of OSC signals is transferred to the network management system (NMS). The principles of Q-factor detection by a numerical calculation method are presented, and also, an on-line supervisory scheme based on DSP and high-speed A/D chip techniques is set up. The results indicate that the tendency of the calculated Q values matches the actual BER, and it's feasible and accurate to implement Q-factor on-line supervision in OSC of OTN.

One of the key technologies of the application of POF in the LAN is the coupling of the source and the POF as well as between the POF. In this article, main and important properties, which have great influences on the coupling efficiency of POF, are studied and discussed in detail.

In this paper, an analytical model for the tapered coupler with large dimension is presented based on BPM. Affections of the length and the angle of the taper section for the coupler on the insert loss and split ratio are discussed in details. According to the results of simulations to the tapered couplers with different lengths and angles, some conclusions are obtained as follows: The amplitudes of the field vary with the change of the lengths and the angle of the coupler. And the center of the field deflects in the plane. According to the change of above relation, optimum length and angle are calculated. Aware with the influence caused by these parameters, it is practical significant to design the coupler in order to avoid the power loss.

The rapid development in both Internet application and emerging optical technology is bringing about fundamental changes in networking philosophies. To support the burst traffic on the Internet efficiently, optical burst switching is a way to streamline both protocol and hardware in building the next generation optical Internet. In this paper, we first give an overview of the optical burst switching schemes and burst reservation concepts. After comparisons, we find that the one called Just-Enough-Time (JET) performs the best and allows service differentiation. In the JET mechanism, a parameter, QoS offset time, acts as a very important character. Then we mainly discuss how to choose an appropriate QoS offset time with a dynamic programming model, which is constructed to find out the balance between the loss probability and the utilization of the buffering. Finally, we propose a bran-new strategy, which changes the QoS offset time according to the load of different service. In this way, we can further improve the utilization of the channel, meanwhile, with the loss probability guaranteed.

In this paper, a novel transmissive-reflective star coupler is proposed for expanding the scale of bidirectional WDM star networks. By combining appropriately the symmetrical transmissive property of conventional N+N passive star coupler with the reflective property of the reflective link, the transmissive-reflective star coupler is carried out. This coupler both reserves the advantages of the conventional reflective N-star coupler and overcomes its shortcomings to make the number of ports connected with nodes in the coupler be up to four times as many as that in the reflective N-star coupler. Besides, not only the bidirectional WDM star network constructed with the coupler has great flexibility of networking, but also its network scale can be expanded conveniently and smoothly on line. So, this WDM network can better satisfy the requirements of communication services at present and in future. At first, the structure of this transmissive-reflective star coupler is introduced. Next, its features are analyzed. Moreover, the required distribution ratios of power splitters in this star coupler are computed. Furthermore, the required gains and output power of optical amplifiers in this star coupler is referred. Finally, a conclusion about the star coupler is given.

Polymer optical fiber (POF) is attracting more and more attention in short distance communication system because of its advantages of low cost, low weight, easy alignment, and easy installation. The very narrow Gaussian laser beams from LDs have compatibility problems with POFs of large core diameter and high numerical aperture. This paper investigates the effect of light source injection conditions on the distributions of POF optical field using beam propagation method (BPM). It is found that appropriate offset launch technology could effectively alleviate the incompatibility. Also the mechanism of this technology improving the system bandwidth is explained.

Laser chaotic synchronization of injection-locked semiconductor lasers with a message signal is studied in this paper, the error formula and the encoding formula are presented. Chaotic cryptography communication with the systems has been numerically simulated.

In this paper, special optical fibers are embedded into #-D braided carbon/epoxy composites to constitute intrinsic microbend fiber optic sensors for internal strain measurement. Samples with embedded optical fibers are braided through four-step method and processed through Resin Transfer Molding (RTM) process. Special measures are taken to prevent damage of the sensors. The microbend optic fiber sensor works well in a three-point bending experiment. The experiments show that the output intensity of the microbend sensor is proportional to the internal strain of the sample while the load increases. Similar results can be achieved as the load decreases. The results show that the embedded microbend fiber optic sensor is fit for internal strain measurement in 3-D braided composites.

In this article, a new method is put forward to research mechanical features of braided material using co-braided optic fiber sensor. Optic fiber sensors can be multi-braided into composites to measure various internal parameters, which overcomes the drawback of ordinary mechanical experimental methods and makes measurement more accurate and reliable. Followings are introduced in detail: the devising of carbon fiber braided composite specimens with co-braided optic, the AEFPI optic sensor adopted and the experiments to measure the tensile strain and thermal strain of specimens. It is the first time to use co-braided AEFPI sensor to research the mechanical features of brading composites and experiment results are satisfying.

In many magneto-optical materials, Faraday rotation is always accompanied by magnetic circular dichroism(MCD, that crystal represents different absorption coefficient of right and left circularly polarization light under magnetic field). In this paper, the theory of (MCD) of magneto-optical materials is introduced. The influence of MCD on polarization dependent optical isolator is analyzed through employing Jones vector and transmission matrix. The analytical formula about the relation of MCD and the insertion loss and isolation ratio of optical isolator is derived. The curve of insertion loss and isolation ratio with respect to MCD demonstrated that MCD degrades much isolation ratio comparing with insertion loss. It is evident from the curve the effect of MCD on isolation ration is general small, but in order to make increase in the isolation as high as possible and the insertion loss as small as possible, crystal with minimum MCD coefficient and maximum rotation coefficient should be chosen. The conclusion is significant to optical isolator optimization designing.

In this paper, we described a kind of structures and the principle about a multi-channel optical switch. we designed a novel revolving single mode optical switch, which based on electronically controlled fiber collimators directing the light to desired output fibers, and the movement of fiber collimator is implemented by the rotation of stepping micro-electromotor. The main parts of the optical switch are two cylinders being carrier of fiber collimators, one of which can revolve driven by stepping micro-electromotor which is controlled by micro-computer. With flexibility of structure,it is easy to design the series of 1xN optical switches. Furthermore, by using two or more revolving axes, we can design reasonably the position of the optical collimators, and get no-blocking 2x2 or 4x4 optical switch matrix. We fabricated a 1×8 single1 mode optical switch, and the experiment results indicate that the technical performance of the optical switch can satisfy requires for changing light channel.

A theoretical study on a long-period liquid-crystal (LC) fiber grating is presented by means of an anisotropic waveguide analysis and the coupled-mode theory with the discretization method. Effective propagation and coupling constants are found for a hollow-core fiber filled with nematic liquid crystal, the optic axis of which is in the direction of the fiber axis. The results show that when uniaxial perturbations of the liquid-crystal director exist in the core by external electric fields, the mode couplings can occur between modes with different azimuth variations as well as between modes with the same. The cross couplings between the fundamental core mode and the transverse-magnetic cladding modes are most strong compared even to the self-coupling of the fundamental core mode, and thus the spectral shift with the growth of the director modulation becomes negligible in the weak-modulation regime. Using the derived theoretical results, we discuss numerical examples of long-period LC fiber gratings with respect to the modulation depth of the director and the polarization states of the fundamental core mode. The characteristics of the LC fiber can be modified in many ways based on the LC material, and the dynamic controllability of LC fiber gratings can have many applications in fiber-optic systems. Thus this theoretical analysis could be utilized for them.

With adoption of wavelength division multiplexing scheme to optical communication systems, multiwavelength optical signal source has drawn considerable attention. The conventional multiwavelength sources usually consist of the same number of lasers as wavelength channels and therefore become bulky and costly. In this paper, we propose and implement a novel multiwavelength generation scheme using a high-birefringence fiber loop mirror in a semiconductor-fiber ring laser. Due to the inhomogeneous gain broadening characteristics of semiconductor optical amplifier, up to 22 channels with 0.8 nm wavelength spacing can be obtained at room temperature.

The radiation induce loss in silica fiber was studied and the way on anti-radiation of silica fiber was discussed. It shows that the colourated positive ions (for example Fe, Cr, Mn, Cu, Co, Ni) in the silica fiber is harmful to the anti-radiation of silica fiber. Because the recovery begins as soon as the radiation induced loss begins, the faster the dose rate is, the smaller the total dose is when the fiber is of failure. The experiment indicates that the pre-irradiation of fiber is of advantage for the anti-radiation of fiber. The results are helpful for the application of silica fiber in radioactive environments.

Popularity of IP technology and fast development of WDM technology is promoting the research of IP over WDM greatly. In this paper, three basic issues concerning IP over WDM directly are discussed. Among them, integrated routing scheme for IP over WDM was mainly investigated, in which three models with protocol extensions were analyzed in detail. In addition, the control plane of integrated routing was also investigated, and MPLS-TE control plane with optical extension was considered as the unified control plane for IP over WDM.

How to transport the control and management information of optical networking is a major concern these days. We compare several means and arrive at a conclusion that OSC (optical supervisory channel) is a better choice. The content of OSC is given and OSC channel wavelength, bit rate and coding method are discussed. An OSC example of WDM metro network are illuminated, which demonstrates the processing operation of overheads in OSC, FDI behavior for three types of failure, and Self-management of OSC subsystem. To fulfill the demand of intelligent and distributed management of optical transport network, an OSC of OC-3 (155Mbps) channel bit rate may be needed in the near future.

In this paper, we present a Proxy-Agent Management Platform, which supports the managed objects of the Optical Cross-Connects (OXC). OXC is a sophisticated WDM network element (NE) that makes the WDM networks reconfigurable. It consists of several sub-NEs, such as 3R modules, Mux/Demux modules, transponder modules, optical switch fabric modules, and operation administration and maintenance processing modules. The OXC network element manager requests and gathers the managed information, alarms, and events from those sub-NEs in the OXC network element, and updates the Management Information Base (MIB) of the OXC managed object existed in the local or remote OXC network element management system. We propose an OXC network element manager with proxy-agent functions which could configure, control, and manage the sub-NEs via an unified access interface on the Common Object Request Broker Architecture (CORBA). The proxy-agent in the OXC network element management system offers its own MIB information to SNMP and/or CMIP manager. The proposed platform achieves high code reusability, provides unified access interfaces between sub-NEs and proxy-agent via ORB, and offers authentication and authorization. The proposed platform is verified on simulated testbed, and shows that managed objects can be added or droped easily to develop an intelligent OXC system.

Asynchronous Transfer Mode - Passive Optical Network (ATM-PON) systems support not only existing narrow-band voice and data service but also general broadband services such as video broadcast services to subscriber using the network topology with passive double star architecture. ATM-PON system integrates various access network configurations into a single integrated platform based on ATM. For flexibility and expandability, surveillance and control for ATM-PON system should be developed modular and hierarchical structure. And, surveillance and control block is developed as distributed real-time block for ATM-PON system. In this paper, we describe the development of distributed surveillance and control for ATM-PON access systems.

We introduce a novel simple current sensor, which is based on a fiber Bragg grating covered by a uniform coat of aluminum thin film. The Bragg wavelength of the fiber grating will shift when the current flowing through the film varies due to the Joule heat generated by the current. The relationship between the square of the current intensity and the wavelength shift is basically linear. In the experiment, we got a current sensitivity of about 2.31x10^MIN3nm(mA)².

By using method of Jones matrix, we analyze all-fiber isolator with polarization maintaining (PM) for optic transmission properties in this paper, the calculated formulas for insertion loss (IL) and backward isolation (IS) can be obtained. The curves of variation of IL IS with relative angle of deviation between nonreciprocal Faraday rotator and non-magnetic rotator as well as PM fiber axes non-aim are given. The results are shown: under ideal condition when optical fiber are non-loss and aiming, IL and IS take (Omega) ₊ and (Omega) _- as symmetrical axes, this moment, IL value is minimum, but IS value is maximum. While those angle error in PM fiber is increase, IL data become large, yet IS data change small. If (Omega) ₊ or (Delta) (theta) are 0.573 degree(s), 0.181 degree(s) and 0.057 degree(s) angle off, IS values have a size of 40dB, 50dB and 50dB, respectively. Big or small to angle error with fiber axes will lead to IL~(Omega) _-, IS~(Omega) ₊ graphs towards horizontal left of right to displacement, moreover, add or reducing to fiber attenuation will bring about IL~(Omega) _-, IS~(Omega) ₊ plots along vertical up or down to shift.

Unlike conventional optical fibers in cylindrical form, a tapered optical fiber is a fiber with its core diameter linearly varied lengthwise. As a new type optical fiber, it can provide a higher coupling efficiency, converge the energy of output light and improve the stability and flexibility of the system, thus widely usable in the fields of high power laser transmission, dynamic position sensing, fluorescent detection, data storage and image sensing, etc. and having many potential applications. This paper summarizes the properties of tapered optical fibers and their actual uses in some fields.

Couple-mode equations for optical fiber are introduced; its simple application to periodic optical fiber due to acousto- optic modulator is discussed, their solutions are obtained.

A few kinds of waveguide materials and optical waveguide technology was studied and all kinds of optical waveguide devices and their applications were reviewed in this paper.

With continuous increasing of demand for the bandwidth in the side of user, building broad-band access network becomes conspicuous. Passive optical network (PON) based on Asynchronous Transfer Mode (ATM), i.e. APON is considered as an ideal solution for the optical access network (OAN). The paper briefly introduces APON access System and it's delaminating. Basing on it, paper focuses on discussing distributed sample de-scrambling in the PON transmission layer. The node of distributed sample de-scrambling is the synchronization between Psedo Random Bit Sequence (PRBS) of transmitter with PRBS of receiver. In term of ITU-T G.983 this paper make logistic analysis to de-scrambling and give circuit for reference. For the more this paper put forward the feasible solution to the distributed sample de- scrambling which implements by FPGA. The figure of Functional Blocks that used for the FPGA design is also provided.

A new kind of optical fiber sensor, transmission moving-grating optical fiber sensor is presented. Optical fiber is used as light-transmitting element in this kind of sensor. Sensitive element is a couple of equal pitch gratings, the one is a fixed grating, the other is a moving grating. Light flux changes as the position of the two gratings change, then after transformed by the photoelectric conversion system, the signals are output as electronic signals. Because of its simple structure and convenient operating, this kind of sensor can be used to measure displacement, strain and other physical quantities. Theoretical analysis of this sensor and experiment results of displacement measurement are provided in this paper. The results indicate that theoretical analysis is identical with experiment results and the sensor has a certain measuring sensitivity.

A flip-flop based 1:4 static frequency divider has been realized in a 0.35micrometers standard CMOS technology. Two 1:2 divider cells achieve the frequency division at more than 5 GHz. Each cell consumes 10mW from a 3.3V supply and occupies about 35X50micrometers +2) die area.

Now, single-mode optical fiber has been widely applied in communication systems and the users of optical fiber have migrated to longer transmission wavelengths, which results in the task of optical fiber measurement becoming more difficult. A method measuring optical fiber properties such as fiber loss and attenuation is optical time domain reflectometer (OTDR) measurement. Conventional OTDRs have a limitation: the trade-off between signal-to-noise ratio and response resolution. This paper presents an approach that applies spectrum-spread techniques to remedy this limitation, and improves dynamic range and reduces measurement time without sacrificing response resolution.