100 Gbit/s, 50 km, and nonrepeated optical transmission employing all-optical multi/demultiplexing and PLL timing extraction

A 16*6.3 Gbit/s, time-and-polarisation division multiplexed optical signal is successfully transmitted through a 50 km dispersion shifted singlemode fibre employing all-optical multi/demultiplexing. A 6.3 GHz timing clock is directly extracted from the multiplexed 100 Gbit/s optical signal by a phase locked loop (PLL) using a travelling-wave laser diode amplifier. A wavelength-tunable modelocked Er/sup 3+/-fibre ring laser and a planar-lightwave-circuit time division multiplexer are newly developed for this experiment.<>     

Distortion In p-i-n Diode Control Circuits

Traditionally, distortion in p-i-n diodes has been thought to be only a function of the carrier lifetime and frequency of operation. This understanding is based on empirical evidence and is not entirely accurate. This paper will discuss the origins of p-i-n diode distortion and study the effects of various devices parameters on distortion performance. Included in the investigation on single-diode circuits will be switching circuits and reflective attenuators. In switch circuits, the analysis shows that distortion can be minimized by maximizing the stored-to-charge resistance ratio in the diode. In attenuators, the analysis shows that maximizing the i-region thickness will minimize distortion, independent of the device carrier life-time. In attenuators where multiple p-i-n diodes are used (the bridged-tee and PI are discussed), maximizing the i-region thickness also minimizes the distortion, independent of carrier lifetime. The model accurately predicts distortion signal cancellation in both single and multiple p-i-n diode circuits.     

New 2-channel multiplexer using polarisation

Experimental results of a new multiplexer using light source polarisations for a wavelength division multiplexing (WDM) transmission system are described. This multiplexer has 2 channels in the 1.2 ?m wavelength region. Insertion losses not taking reflection losses of lenses into account are estimated to be less than 0.25 dB. This multiplexer is applicable only in laser diode systems.     

Theoretical Analysis of Intermodulation Distortion of Reflection-Type IMPATT Amplifiers

The basic equations for a reflection-type IMPATT amplifier are used to derive expressions for the output when the amplifier is driven by a multifrequency input signal. The third-order intermodulation distortion is expressed and graphically presented for various diode, circuit, and signal parameters. The results provide a guideline for designing amplifiers with minimum intermodulation distortion or prescribed distortion level.     

单模半导体激光器等效电路模型

介绍了单模半导体激光器的大信号、小信号及噪声等效电路模型，给出了确定模型参数的一般方法，并在ＰＳＰＩＣＥ中以电路宏模型的方式实现了激光器的大信号模型，对激光器小信号调频响应和大信号非线性失真特性进行了计算机时域模拟。     

利用非线性光学环路镜实现非归零码脉冲到归零码脉冲的变换

利用非线性光学环路镜（ＮＯＬＭ）成功地实现了非归零（ＮＲＺ）脉冲向归零（ＲＺ）脉冲的变换。实验中采用 开关激光器产生的超短光脉冲作为控制光、锁模激光器输出光经外调制后得到的光轮训珧。对变换信号采用时分复用（ＴＤＭ）方式得到了２０ＧＨｚ光信号。     

Eight-channel bidirectional WDM add/drop multiplexer

The authors propose and demonstrate an eight-channel reconfigurable bidirectional wavelength division multiplexed (WDM) add-drop multiplexer in which all channels can be added/dropped independently in either direction. The performance of the bidirectional WDM add/drop multiplexer is experimentally studied for a data rate of 10 Gbit/s per channel, providing an overall capacity of 80 Gbit/s. It is found that the performance of the add/drop multiplexer is not degraded by a backward propagating signal     

Experimental demonstration of a three channel WDM system over 110 km using superluminescent diodes

The experimental demonstration of a three channel WDM (wavelength division multiplexer) system over 110 km of single mode optical fibre at 140 Mbit/s using a high power superluminescent diode and an erbium fibre amplifier is reported.<>     

Intermodulation Distortion Analysis of Reflection-Type IMPATT Amplifiers Using Volterra Series Representation

Intermodulation distortion generated in a stable IMPATT amplifier is analyzed using Volterra series representation. An IMPATT amplifier model, which takes into account the interaction between the nonlinearities of the diode and its embedding circuitry, is described. The Volterra transfer functions are derived for this model. Nonlinear terms up to and including the fifth order are considered. Intermodulation distortion products are calculated for a low-level input signal consisting of two tones. The results of this analysis are extrapolated into the direction of increasing output power in order to obtain the third-order intercept point. Further, closed form expressions for the third-order intermodulation IM/sub 3/ and intercept point P/sub I/ are derived. The distortion of a specific 6-GHz IMPATT amplifier is evaluated for illustrative purposes; the predicted distortion behavior compares favorably with experimental results.     

Theory of Noise and Transfer Properties of IMPATT Diode Amplifiers

A theory is formulated which describes quantitatively the noise and transfer properties of IMPATT diode reflection-type negative resistance amplifiers. This theory is based on the method used in the large-signal theory of noise in IMPATT diode oscillators by the present authors. The theory takes into account the signal dependence of the noise generation in the diode, the noise and/or modulation present in the input signal, and also the intermodulation effects occurring between the various frequency bands. The equations are conveniently arranged in matrix form; such a formulation makes it easier to obtain quantitative results in terms of measurable noise and modulation parameters. Agreement between measured and theoretically predicted AM and FM noise of injection-locked oscillators is good. The usefulness of the theory is illustrated by results of calculations on minimum attainable noise of a given amplifier, maximum noise allowable on the input signal, AM-FM conversion, phase distortion, bias modulation, and the correlation between various types of noise.     

Preclipping experiment for subcarrier-multiplexed AM/64QAM opticaltransmission

Bit-error-rate degradation of the 64QAM signal due to clipping distortion caused by overmodulation at the laser diode is compensated for by preclipping for subcarrier-multiplexed AM; 64QAM optical transmission. The worst composite distortions of CSO<-60 dBc and CTB<-65 dBc have been achieved in the 40-channel AM signal band. It has also been confirmed that preclipping is more effective than Reed-Solomon (204, 188) error correction against clipping distortion     

18 Gbit/s monolithically integrated 2:1 multiplexer and laser driving using 0.3 mu m gate length quantum well HEMTs

A monolithically integrated 2:1 multiplexer and laser diode driver was developed, using AlGaAs quantum well HEMTs of 0.3 mu m gate length. The DC and modulation current is 25 and 45 mA, respectively. Open eye diagrams were measured at bit rates up to 18 Gbit/s with pseudorandom data streams.<>     

100 Gbit/s optical signal generation by time-divisionmultiplication of modulated and compressed pulses from gain-switcheddistributed feedback (DFB) laser diode

An all-optical spatial time-division multiplexer is demonstrated using fibre-type 2×2 couplers and fibre delay lines. 100 Gbit/s modulated optical signals are successfully generated by 32-times multiplication of 3.125 Gbit/s, 6 ps compressed pulses, from a gain-switched DFB laser diode     

STS-768 multiplexer with full-rate output data retimer in InP HBT

A 16:1 STS-768 multiplexer IC has been designed and fabricated using the Vitesse Semiconductor VIP-1 process. This IC is part of a complete chip-set solution for a 40-Gb/s STS-768 optical communication transceiver module. The multiplexer IC features a full-rate clock multiplication unit and a data retimer in the output stage to reduce duty-cycle distortion and jitter in the output data eye. Because of its strict timing requirements, this approach needs fast logic gates with a very low gate delay. The Vitesse VIP-1 process, with 150-GHz f/sub t/ and 150-GHz f/sub max/ heterojunction bipolar transistor, is an obvious choice to implement this IC. The multiplexer IC typically dissipates 3.6 W from -3.6-V and -5.2-V power supplies. This paper discusses the design and development of a 40-Gb/s 16:1 multiplexer IC including current-mode logic gate circuit design, divide-by-two, 40-GHz clock tree, voltage-controlled oscillator, clock multiplication unit, and output driver. Layout design and package design are also discussed due to their significant roles in the IC performance.     

Wavelength-selective 1/spl times/K switches using free-space optics and MEMS micromirrors: theory, design, and implementation

The design and performance of several generations of wavelength-selective 1/spl times/K switches are reviewed. These optical subsystems combine the functionality of a demultiplexer, per-wavelength switch, and multiplexer in a single, low-loss unit. Free-space optics is utilized for spatially separating the constituent wavelength division multiplexing (WDM) channels as well as for space-division switching from an input optical fiber to one of K output fibers (1/spl times/K functionality) on a channel-by-channel basis using a microelectromechanical system (MEMS) micromirror array. The switches are designed to provide wide and flat passbands for minimal signal distortion. They can also provide spectral equalization and channel blocking functionality, making them well suited for use in transparent WDM optical mesh networks.     

Nonlinear distortion performance of narrow stripe-geometry lasers

Using the theoretical normalised current-light characteristic of a narrow stripe-geometry laser, an empirical formula is developed for the normalised light-current characteristic. Using this formula, closed-form expressions, in terms of the modified Bessel functions, are obtained for the nonlinear distortion components in the light resulting from exciting the laser diode by a multi-tone input current. These formulas can be used to predict the large signal performance of a narrow stripe-geometry laser diode by using simple hand calculations.     

用于SDH STM-4光发射机的4:1复接器和激光驱动器

采用CSMC0.6μm CMOS工艺设计实现了速率为622Mbps的4∶1复接器和激光二极管驱动器电路。4∶1复接器采用树型结构,由3个2∶1复接器组成。激光二极管驱动器电路由两级差分放大器和一级电流开关构成,级间采用源级跟随器隔离。电路芯片尺寸为1.5mm×0.7mm。电路采用单一正5V电压供电,功耗约为900mW。测试结果表明,电路的最高工作速率超过1.25Gbps速率,输出最大电流超过85mA。     

实用化宽带半导体激光器组件的研制及其特性的研究

使用ＤＣ－ＰＢＨ型激光二极管芯片，设计制作了实用化封装形式的宽带半导体激光器组件，在理论上和实验上研究了组件的封装模型、小信号频率调制特性和非线性失真，其光响应为３ｄＢ，带宽大于２ＧＨｚ．该器件可满足六次群光通信系统的带宽要求，也可用于ＧＨｚ级微波副载波光通信系统．     

空间光通信视音频同步无线传输技术研究

设计并演示一个可实现视音频信号同步无线传输的自由空间光通信系统。该系统包括信号发生、调制和接收模块。对由信号发生模块输出的视音频信号进行时分复用(TDM),复用信号以电信号形式作用于声光调制器(AOM)并将其加载于入射到AOM的激光束上,AOM输出调制光信号,最后接收模块还原出视音频信号。整个通信系统带宽为6.7 MHz,通过电-光-电转换过程,将时分复用和声光调制相结合实现了视音频信号同步无线传输。本系统针对具体工作环境,自建核心电路:时分复用/解复用电路和输出光端机电路,采用单片机调控输出信号质量。实验证明该系统具备成本低廉、实用性强和灵活性高等优点,为监控系统、应急通信等应用场合提供一种简易有效的视音频信号同步无线传输方案。     

Optoelectronic switches and multigigabit 8:1 time multiplexer

Optoelectronic metal-semiconductor-metal (MSM) switches in InP were studied and used as sampling elements in a digital time division multiplexer. It was found that switch performance can range from the depletion-layer photodiode to the photoconductor regime as the activating light intensity increases. The multiplexer had an 8:1 ratio, a 2-V signal bias, >25-dB S/N, and a serial rate of at least 2.5 Gb/s. This multiplexer with its high S/N and the timing stability intrinsic to fiber delay lines will be advantageous for high-speed digital communications