一种全光3R再生方案的研究

研究全光3R再生技术,给出了一个利用非线性光纤的自相关调制和全光异或门对光信号的再整形仿真方法.使用软件Optisystem分别对时钟提取和异或门的实现制进行了仿真实验.方案整形后获得的3R再生信号的质量得到改善.     

全光再生中的时钟恢复技术

随着超高速大容量的光网络的发展,全光再生技术成为目前的研究热点.其中全光的时钟恢复是全光再生技术的重要组成部分, 是全光再生中定时、整形的基础.文章在阐述了目前各种全光时钟恢复技术研究所取得的进展的基础上,分析了各类技术的优缺点,并对进一步研究作了展望.     

基于放大反馈激光器高速全光时钟提取的研究

为了研究放大反馈激光器全光时钟提取的性能,采用单边带相位噪声功率谱积分的方法,对40Gbit/s无恶化信号和噪声恶化信号分别进行了时钟提取实验,计算了所提取时钟的时间抖动。同时还测量了放大反馈激光器的锁定范围。通过实验取得了恶化前后所提取时钟的时间抖动分别为130fs和150fs,放大反馈激光器的锁定范围为234MHz。结果表明,基于放大反馈激光器的全光时钟提取方案对噪声恶化具有较强的容忍度,而且具有较宽的锁定范围。这一结果对于全光时钟提取技术的进一步发展具有重要意义。     

3R再生中的时钟提取技术

论述了目前所采用的具有代表性的全光3R（再放大、再整型和再定时）再生中的时钟提取方案原理,进而比较了各个方案的优缺点,为在不同情况下选择合适的时钟提取方案提供了一定的依据。     

F-P滤波器改进与全光3R时钟分量恢复

详细阐述了全光3R再生的原理,介绍了全光3R再生中的几种时钟恢复技术,详细分析了法布里一珀罗（Fabry—Perot）谐振腔的时钟恢复技术,并在此基础上提出了一种改进的F-P滤波器的方法。仿真结果表明,这种方法的工艺难度低,时钟恢复效果良好,适合于高速率时钟提取。     

全光3R再生中时钟恢复技术的研究

全光3R再生(再定时、再整形、再放大)是全光通信网的核心技术之一,其中时钟恢复是再定时和再整形的基础.时钟恢复输出的时钟脉冲须具有高速、低相位噪声、高灵敏度、偏振不敏感和稳定的特点.首先介绍了3R再生的研究背景和研究现状,讨论了全光3R再生的基本原理,重点分析了3R再生中所使用的几种时钟恢复方法,并对其进行了比较.     

基于DFB激光器实现波长转换误码特性的研究

作为自动交换光网络中的核心器件,全光波长转换器将在全光通信系统中发挥重要作用.根据半导体激光器实现波长转换的理论模型,重点研究了基于DFB实现波长转换器的误码特性.包括工作电流、输入信号光功率等参量对消光比、误码率的影响.并利用自行搭建的基于DFB实现波长转换的实验平台,进行了实验分析,发现理论分析结果和实验数据十分吻合.这对于优化基于DFB结构的全光波长转换器有重要参考价值.     

基于数据抽运的光纤光参量放大的4×40Gb/s多波长全光3R再生实验研究

提出了一种新型的基于数据抽运的光纤光参量放大(FOPA)的多波长(4×40 Gb/s)全光3R再生实现方案。与已有的利用光参量放大技术再生不同的是,所提方案利用4路恶化的数据信号作为抽运光,同时,分析了其再生机理。实验结果表明,对于1码和0码的噪声均有较好的抑制。利用波长变换和高Q值(1000)的法布里-珀罗(F-P)滤波器进行时钟提取,得到均方根(RMS)抖动仅为180 fs的高质量时钟。在多波长全光判决部分,采用了正交极化和双向注入的方法来抑制4个恶化信号之间的相互串扰。最终实现了4路信号的信噪比改善值分别达到2.21、2.79、2.72和1.99的再生实验。     

基于太赫兹光非对称解复用器的全光倍频技术

太赫兹光非对称解复用器(TOAD)是一种全光信号处理领域中常用的器件,其具有响应速度快、可集成、稳定性好等优点。本文提出了一种基于TOAD的全光时钟倍频技术方案。通过模型仿真,模拟对TOAD输入直流光,在时钟脉冲前后沿附近会产生双峰输出现象,以此来分析TOAD的开关特性,研究了控制光能量、开关窗口大小、半导体光放大器增益恢复时间等因素对双峰输出特性的影响。对光时钟信号进行了全光二倍频、三倍频和四倍频的仿真,从频谱上观察,倍频准确,并且在实验上实现了200 Mb/s和1 Gb/s时钟的全光二倍频,与仿真结果相符。     

空间激光通信网络中的全光相位再生技术

围绕空间激光通信网络中高速数据多跳传输应用需求,针对相位调制激光链路经过空间长距离传输后信号质量劣化的问题,研究了基于相位敏感四波混频参量效应实现二进制相位调制高速激光信号的全光相位再生技术。利用Matlab软件数值分析了全光相位再生系统的影响因素,并基于OptiSystem仿真平台搭建了全光相位再生系统。结合高轨-地面站空间激光通信系统链路预算,对速率为10 Gbit/s的DPSK信号光经背靠背、相位噪声劣化以及劣化后全光相位再生处理三种传输场景进了对比分析。模拟仿真结果与数值分析结果均表明,与劣化后未经再生处理的系统相比,全光相位再生处理后的系统误码率平均优化4个数量级,信噪比提升约3 dB,表明该空间激光通信全光相位再生技术可实现相位调制信号的全光相位再生,能够有效提升空间相干激光通信系统的性能,可以应用于空间高速激光通信网络中继节点处的全光数据中继等方向。     

Self-Pulsating Amplified Feedback Laser Based on a Loss-Coupled DFB Laser

Monolithic self-pulsating semiconductor lasers called amplified feedback lasers (AFLs) can generate high-frequency self-pulsations according to the concept of a single-mode laser with shortly delayed optical feedback, which consist of a distributed-feedback (DFB) laser, a phase control, and an amplifier section. Since mode degeneracy of the DFB section, which should operate as a single-mode laser, affects the self-pulsation, single-mode characteristics of the DFB section are critical for the self-pulsation. The effect of a complex coupling in the DFB section on the self-pulsation is numerically analyzed to reveal that the complex coupling provides a wide operation range for the self-pulsation. Also, self-pulsating AFLs based on a loss-coupled DFB laser are experimentally demonstrated to verify the self-pulsation characteristics and the capability for all-optical clock recovery.     

Self-pulsation in multisection laser diodes with a DFB reflector

A novel self-pulsation regime is observed in multisection laser diodes which consist of a loss-coupled distributed-feedback (DFB) section, a phase control section, and gain sections, where 10-GHz self-pulsation due to compound cavity mode beating has been reported with the DFB section operated as a single-mode laser. When the DFB section is below threshold current, the devices give the self-pulsation in a very wide operating range. We attribute the pulsation to passive mode-locking and also confirm that this structure is applicable to 40-GHz operation.     

Optical generation and sideband injection locking of tunable 11-120GHz microwave/millimetre signals

It is shown that two-section gain-coupled DFB lasers with large section lengths and weak distributed feedback coupling exhibit a self-pulsation tuning range greater than reported previously. The phase noise of a sideband injection locked self-pulsation is measured and the jitter introduced by the self-pulsing laser found to be negligible     

40 Gbit/s all-optical clock recovery using two-section gain-coupledDFB laser and semiconductor optical amplifier

40 Gbit/s wavelength and polarisation insensitive all-optical clock recovery using a two-section distributed feedback (DFB) laser has been demonstrated. The polarisation sensitivity of the two-section DFB laser was solved by converting incoming data onto a local laser through cross-gain modulation using a semiconductor optical amplifier. The scheme has a sensitivity of -13 dBm     

An Ultralow Noise and Narrow Linewidth λ/4-Shifted DFB Er-Doped Fiber Laser With a Ring Cavity Configuration

We report a polarization-maintaining lambda/4-shifted distributed feedback (DFB) Er-doped fiber laser with a ring cavity configuration. The ring cavity suppressed the self-pulsation of the stand-alone Er-doped DFB fiber laser. The laser with a 57-m-long ring cavity achieved single-longitudinal-mode operation, a linewidth as narrow as 6 kHz, and relaxation-oscillation-free noise characteristics.     

Distinction between multimoded and singlemoded self-pulsations-inDFB lasers

DFB lasers with split contacts are shown, by large signal dynamic modelling, to self-pulsate at gigabit frequencies. Two different self-pulsation schemes are discussed: where the laser switches between the higher and lower stop band modes, and where the laser pulsates around a single mode. The second scheme can yield self-pulsation frequencies beyond 20 GHz. Comparisons are made with experimental results     

High-frequency pulsations in DFB lasers with amplified feedback

We describe the basic ideas behind the concept of distributed feedback (DFB) lasers with short optical feedback for the generation of high-frequency self-pulsations and show the theoretical background describing realized devices. It is predicted by theory that the self-pulsation frequency increases with increasing feedback strength. To provide evidence for this, we propose a novel device design which employs an amplifier section in the integrated feedback cavity of a DFB laser. We present results from numerical simulations and experiments. It has been shown experimentally that a continuous tuning of the self-pulsation frequency from 12 to 45 GHz can be adjusted via the control of the feedback strength. The numerical simulations, which are in good accordance with experimental investigations, give an explanation for a self-stabilizing effect of the self-pulsations due to the additional carrier dynamic in the integrated feedback cavity.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

Intensity noise suppression in fibre DFB laser using gain saturated SOA

Experimental results of a simple, all-optical technique to reduce low-frequency intensity noise in an Er-Yb codoped fibre distributed feedback (DFB) laser are reported. This method utilises the gain dynamics of a saturated semiconductor optical amplifier (SOA) to produce a reduction of 30 dB in the relaxation oscillation noise component of the fibre laser.     

All Optical Wavelength Conversion from 1.3μm to 1.55μm Using Two—segment DFB Lasers^①

All-optical wavelength converters are expected to become key components in the future broadband networks.Here a two-segment DFB laser for the first time is used as an all-optical wavelength converter.Using this laser,all-optical wavelength conversion from1.3μm tp 1.55μm is demonstrated。