二阶偏振模色散高速光纤通信的影响及补偿

讨论了二阶偏振模色散对光脉冲的影响,模拟结果表明,二阶偏振模色散对信号影响起主要作用的是去偏振项,使得信号波形边缘出现能量过冲;同时也讨论了二阶偏振模色散补偿的方法,利用二段偏振模色散补偿器对二阶偏振模色散进行了有效的补偿,并给出了补偿的实验结果.     

一种高速光纤通信高阶偏振模色散补偿的前馈信号提取方法

建立了一种实时提取一阶和二阶偏振模色散的模型,可以直接得到偏振模色散的大小和方向。通过数值模拟将得到的偏振模色散大小与从琼斯矩阵理论中计算的结果进行比较,我们模拟结果与理论计算值在差分群时延为一个比特周期内较好相符。从得到的偏振模色散矢量的大小和方向信息可以为高阶阶偏振模色散补偿提供前馈信息     

实验环路PMD统计特性的研究

研究了光纤循环环路的偏振模色散统计特性，利用琼斯矩阵法对光纤循环环路的偏振模色散统计特性进行了数值模拟。结果表明，循环环路中与单一链路中的偏振模色散统计特性相比，无论是一阶还是高阶特性都有明显的区别。     

初始啁啾对WDM系统中偏振模色散的影响

依据耦合非线性薛定谔方程,利用分步傅利叶方法求耦合方程的数值解,仿真分析了初始啁啾对波分复用系统中偏振模色散的影响。仿真结果表明：输人功率较小时,正啁啾与二阶色散共同作用对偏振模色散进行抑制;输入功率较大时,正啁啾与二阶色散、非线性效应共同作用部分补偿了偏振模色散所造成的脉冲展宽;啁啾不宜过大,存在最佳值。     

偏振模色散统计特性的研究

利用动态方程研究了偏振模色散矢量的统计特性 ,分别用统计系综和频率系综两种方法进行数值模拟。数值结果表明 ,统计系综和频率系综两种方法的结果一致。在大归一化距离条件下 ,均方根时延的平方随归一化距离线性变化 ;偏振模色散矢量的各个分量服从高斯分布 ,差分群时延服从麦克斯韦分布 ;偏振模色散矢量弥散于整个邦加球     

偏振模色散仿真器特性研究

光纤通信线路的偏振模色散已成为高速、长距离光纤通信系统发展的主要障碍之一 ,其特性、测量以及补偿方法的研究成为目前光纤通信研究热点之一。偏振模色散仿真器 ,用于仿真传输链路的偏振模色散特性 ,不仅可用于偏振模色散补偿器 ,也可用于高速长距离光纤通信系统的规划设计等。本文分析了光纤偏振模色散仿真器的研究现状 ,归纳总结了现有偏振模色散仿真器的设计原理和结构特征 ,并用蒙特卡罗法对常用的偏振模色散仿真器的特性进行了数值模拟     

高速光通信偏振模色散补偿前馈信号提取方法

为了得到高阶偏振模色散的前馈信息,采用数值模拟的方法,通过一种实时提取1阶和2阶偏振模色散的模型,直接得到了偏振模色散的大小和方向。将模拟得到的偏振模色散大小与从琼斯矩阵理论中计算的结果进行比较,结果表明,采用该模型的模拟结果与理论计算值在差分群时延为一个比特周期内符合较好。从得到的偏振模色散矢量的大小和方向信息可以为高阶偏振模色散补偿提供前馈信息。这一结果对偏振模色散的前馈补偿系统的设计具有参考价值。     

光纤偏振模色散的两级自适应补偿器

成功地研制了对于10Gbit／sNRZ码和RZ码光纤通信系统的两级偏振模色散自适应补偿实验系统。实验中运用光纤链路中偏振度(DOP)作为反馈控制信号，采用名为PSO(Parti—cleSwarmOptimization)的优化方法作为偏振模色散的搜索和跟踪控制算法。实验证明，该补偿系统可以同时补偿一阶和二阶偏振模色散，补偿搜索时间为几百毫秒，跟踪系统对于链路中突发的偏振模色散变化的响应恢复时间小于20毫秒，实现了准实时的一阶和二阶偏振模色散自适应补偿与跟踪。     

晶体型二阶偏振模色散模拟器

报道了一种新型的二阶晶体型偏振模色散(PMD)模拟器,其由3片可产生不同的一阶PMD差分群延迟(DGD)的晶体和1个法拉第旋转器组成,法拉第旋转器理论上可在180°内连续变化。该二阶PMD模拟器实验上能近似模拟从50到200 ps2的二阶PMD。给出了二阶PMD随偏置电压变化的曲线。实验表明,该器件输出的重复性好,响应时间小于1 ms,实验值与理论值近似符合。     

几种偏振模色散(PMD)野外测试方法的比较

报道了对一根长168km的海底光缆，采用两种方法测量其偏振模色散的研究。分析实验结果，得出了偏振参数的统计特性及其时间涨落。其平均差分群时延达到约13ps，表明偏振色散对色散位移光纤的影响比对标准突变折射率光纤的影响更严重。而偏振耦合的相关长度对被测光纤所造成的干扰，相对于链接长度来说是不可忽略的因素。     

On the second-order approximation of PMD

A second-order polarization mode dispersion (PMD) approximation based upon the pulse-width distortion has been studied. It shows that a complete second-order approximation should include the second derivative of the PR-ID vector as well as the first derivative of the PMD vector. Second-order pulse distortions are explicitly expressed including a `first-order' term involving principal states of polarization (PSP) of the pulse and a second-order term involving the beating between fiber chromatic dispersion and effective PMD chromatic dispersion. An analytical result is derived for the probability of second-order PR-ID power penalty. It shows that the mean PMD of the fiber should be restricted to 26 ps and 18 ps, respectively for an optical link with zero and 850 ps/nm chromatic dispersion, in order to maintain a one dB second-order PMD power penalty with a probability below 10^-6 at a data rate of 10 Gb/s. The analysis also indicates that a second-order PMD compensator can be used as a dynamic chromatic dispersion compensator     

基于脉冲位置调制系统的偏振模色散监测方案

为了实现对脉冲位置调制传输系统光纤信道中偏振模色散的动态监测,提出了一种新型偏振膜色散监测方案,并基于监测原理构建了数学模型。该方案基于单边带内不同偏振信号相位差实现,具有结构简单、易于实现、成本低等优点。结果表明,本方案可以实现对光信号的差分群延时与偏振态的动态监测,即当差分群延时在0ps~100ps范围内时,可准确监测;同时证实了其与信号速率关系较小,能够适应不同速率的系统,且可对脉冲位置调制传输系统的偏振模色散进行实时动态监测。该方案是一个高效可行的偏振模色散监测方案。     

Versatile integrated PMD emulation and compensation elements

Highly versatile building blocks for polarization-mode dispersion (PMD) emulation and compensation are demonstrated using tunable all-pass filters fabricated in 4%-index-contrast planar waveguides. While the all-pass filters can approximate any phase response, the complexity in setting the individual filter parameters is minimized by restricting the all-pass filter responses to realize a range of differential delays, dispersion, and dispersion slope. A single section can approximate first-order or a higher-order PMD term or emulate chromatic or higher-order dispersion. A differential group delay (DGD) tuning range over 100 ps is demonstrated for 10 Gb/s and 25 ps for 40 Gb/s data. Second-order PMD with a tuning range of 255 ps/sup 2/ and third-order PMD with a range of 2430 ps/sup 3/ are also demonstrated. The larger index contrast required for the ring-resonator-based all-pass filters is advantageous in reducing the thermooptic response time to achieve polarization rotation speeds on the order of 0.1 /spl mu/s/degree. The device is interferometrically stable and compact in size. It can be fully integrated, scaled to many sections, and can implement a variety of PMD synthesis and statistical-emulation approaches.     

The Second Order PMD in Optic Fiber and Compensation Experiment

1　Introduction　Inhigh speed /long distanceopticalfibertransmissionsystem ,PMDisoneofthemainfactorslimitingthebitrateandthetransmissiondistance ,becomingespeciallyimportantasthebitrateincreaseshigherthan 2 5Gb/s .TheinstantaneousPMDoftransmissionlineischangingfromtimetotimeandfromfrequencytofre quencyrandomly .InfrequencydomainPMDcanbeex pressedbytheTaylorexpansionatcenterfrequencyanddividedintofirstorder ,secondorder ,…ofwhichhigh erthansecondareallcalledhighorderPMD[1] .Fromfrequenc…     

Dynamic PMD compensator for 40 Gb/s PM-DQPSK system

The adaptive polarization mode dispersion(PMD) compensation in high-speed transmission system has become more and more necessary for the link PMD causing strong signal distortions.A dynamic adaptive PMD compensator in 40 Gb/s polar-multiplex differential quadrature phase shift keying(PM-DQPSK) system is reported.Experimental results show that the PMD compensator can track the average polarization state variation at 65 rad/s without any lost of the optimum tracking.The 1st-order PMD compensation is demonstrated experimentally,and the compensator can increase the maximal tolerable PMD value by 26 ps from 17 ps to 43 ps in an optical transmission system.     

160 Gbit/s OTDM signal transmission over 26 km photonic crystal fibre

A 160 Gbit/s (=10 Gbit/s X 16) optical time-division multiplexing (OTDM) signal is successfully transmitted over a 26 km-long photonic crystal fibre (PCF). The transmission induced signal pulse broadening is suppressed to only 0.2 ps (from 2.1 to 2.3 ps) because the fabricated PCF has low polarisation-mode dispersion (PMD) of 0.1 ps/km^1/2, and the total chromatic dispersion of the transmission line is suppressed to 0.015 ps/nm by using a dispersion-compensation fibre. The transmitted signal is demultiplexed using four-wave mixing in a 100 mlong dispersion shifted fibre, where a phase modulation-based 10 GHz pump pulse source is newly adopted.     

Large PMD Compensated by Four Free Degrees in OTDM System

By introducing a two-stage polarization mode dispersion (PMD) compensator after a optical fiber link with a large PMD,over 270 ps first-order and 2 000 ps2 high-order PMD was compensated. The results show that the two-stage compensator can be used to PMD compensation in the 20 Gb/s optical time division multiplexing system with 60 km high PMD fiber. After compensating, the 270 ps DGD is changed into max. 7 ps. Moreover,the tunable FBG has a function of dispersion compensation.     

Measurement of second-order polarization-mode dispersion vectors inoptical fibers

A polarization-mode dispersion (PMD) measurement technique is described that allows the determination of second- and higher order PMD vectors in optical fibers. The algorithm, based on Muller matrices, requires the launch of only two polarizations per wavelength and uses large rotation angles as well as interleaving to attain low-noise high-resolution PMD data. It has been applied to fibers ranging from 2 to 40 ps in mean PMD     

初始啁啾和偏振效应对光纤通信系统的影响

采用多重重要抽样方法,对受偏振模色散(PMD)和偏振相关损耗(PDL)联合影响的10 Gbit/s光通信系统在不同脉冲初始啁啾和占空比下的性能进行了数值仿真.给出了PMD=10 ps和PDL=1、1.5 dB时开关键控(OOK)和差分相移键控(DPSK)调制的光传输系统的功率代价分布和系统失效概率.发现在不同占空比下,系统性能有明显不同;引入适当的初始啁啾(如啁啾因子C=0.5),有利于提高系统的性能.