高速光纤通信系统中高阶PMD的优化建模

为了评估随机变化的偏振模色散(PMD)(包括一阶和二阶PMD)使系统信号裂化的程度,降低其对高速光纤通信系统传输速率和传输容量的不利影响,在斯托克斯空间中推导了偏振模色散(PMD)矢量的数学表达式。对PMD效应所导致的脉冲展宽进行了数学分析,给出了差分群时延(DGD)的变化、一阶PMD矢量和二阶PMD矢量方向的变化对脉冲展宽的影响。通过数学推导得出,在大多数情况下,二阶PMD无法完全补偿,需通过控制单元的调整使其对系统的影响达到极小值。通过实验分析,得到了和数学推导中同样的结果,从而证明了模型的正确性。     

单模光纤中二阶偏振模色散的测量及其统计特性研究

在高速光纤通信系统中,二阶偏振模色散将引起脉冲信号的展宽和畸变,严重影响系统的传输性能。应用琼斯矩阵本征分析法,测量了光纤的二阶偏振模色散,并对二阶色散的平行分量、消偏振分量、PCD和退极化率进行了详细的分析,得到了二阶PMD随波长的分布情况和统计特性。对二阶偏振模色散的补偿有一定的指导意义。     

偏振度作为反馈信号进行偏振模色散补偿的研究

对40Gb／s光纤通信中归零码和非归零码光脉冲的偏振度随二阶偏振模色散的变化规律进行了数值模拟,结果表明由于二阶偏振模色散的影响,偏振度的变化趋势呈现出震荡性,二阶偏振模色散对归零码的偏振度要比非归零码的偏振度影响明显;同时搭建了偏振模色散补偿系统,对系统进行数值模拟和实验所得到的结果都表明,以偏振度作为反馈信号,采用粒子群优化算法作搜索算法能够有效地对归零码和非归零码系统的一阶及高阶偏振模色散进行自适应补偿。     

单模光纤偏振模色散设计特性的分析

用琼斯矩阵本征分析法对偏振模色散各参量的统计特性进行了分析，得到了一阶和二阶偏振模色散的统计规律，并给出了二阶偏振模色散各参量与一阶偏振模色散各参量之间的比例关系，对二阶偏振模色散的获取，补偿和系统设计均有指导意义。     

偏振模色散引起的脉冲展宽对接收灵敏度及频谱的影响

在10Gbit/s以上的光纤通信系统中，偏振模色散的影响已不可忽略，它可以引起信号脉冲的展宽，使接收系统的误码率上升，分析了偏振模色散引起的脉冲展宽对接收灵敏度及接收信号频谱的影响，并进行了实验验证，对进行偏振模色散的自动补偿具有重要意义。     

单模光纤偏振模色散统计特性的分析

用琼斯矩阵本征分析法对偏振模色散各参量的统计特性进行了分析 ,得到了一阶和二阶偏振模色散的统计规律 ,并给出了二阶偏振模色散各参量与一阶偏振模色散各参量之间的比例关系 ,对二阶偏振模色散的获取、补偿和系统设计均有指导意义。     

光纤偏振效应导致脉冲展宽的解析模型

在10Gb／s,尤其是40Gb／s以上高速光纤通信系统中,光纤的偏振特性已成为限制系统传输距离的主要因素之一。光纤的偏振效应主要包括偏振模色散和偏振依赖损耗。而脉冲均方根展宽是判断信号传输性能的一个主要物理量。本文讨论了光纤线路偏振模色散与偏振相关损耗的相互作用及对信号脉宽的影响。给出了线路偏振模色散矢量和偏振相关损耗矢量之间的关系式,并基于严格的数学方法,导出了在光纤偏振模色散和偏振相关损耗共同作用下的信号均方根脉宽变化的解析形式,同时考虑了光纤色散,啁啾等。该模型可用于分析高阶偏振模色散和偏振相关损耗,任意线性光纤通信系统脉冲展宽分析。     

用庞加莱球法测量二阶偏振模色散

用庞加莱球法测量单模光纤中的二阶偏振模色散，并对二阶偏振模色散的各个分量的统计特性及其影响进行了分析。对75km的G．652普通单模光纤的二阶偏振模色散进行了测量，并对二阶偏振模色散的平行分量、垂直分量、偏振相关色散和消偏振项进行了详细的分析．得到了二阶偏振模色散随波长的分布情况、统计特性以及偏振主态随波长的变化情况。从统计结果可以得到．与偏振相关色散项相比，消偏振项在二阶偏振模色散中起主要作用。该研究对二阶偏振模色散的补偿有一定的指导意义。     

偏振模色散矢量的研究

研究了无损光纤的密勒矩阵,进而得出了偏振模色散矢量的解析表达式、主偏振态对应的斯托克斯矢量的解析表达式,以及高阶偏振模色散矢量的解析表达式.这些解析表达式是由光纤参数决定的.讨论了局部偏振模色散矢量与整体偏振模色散矢量的关系,讨论了利用偏振模色散矢量进行偏振模色散补偿的原理.引入了偏振模色散补偿元件的偏振模色散补偿矢量C,具体计算了正规的非圆光波导类的补偿元件的C.从理论上证明了仅仅利用一个正规的非圆光波导类的补偿元件,例如一根保偏光纤或是一个双折射晶体,是不能实现偏振模色散补偿 关键词： 偏振模色散 密勒矩阵 色散补偿 主偏振态斯托克斯矢量     

基于偏振度椭球的PMD补偿的前馈信息提取方法

通过建立一个简单的模型推导了偏振模色散与偏振度椭球的关系式,可以直接从偏振度椭球的长轴和短轴得到偏振模色散的大小.将得到的一阶偏振模色散大小与理论上从琼斯矩阵中计算的结果进行比较,发现在差分群时延小于20 ps时,模拟结果与理论计算值较好相符.分析了如何从偏振度椭球的长轴判断偏振模色散矢量的方向.因此,从得到的偏振模色散矢量的大小和方向信息可以为一阶偏振模色散补偿提供前馈信息.     

Impacts of polarization mode dispersion on the pulse-width with considering initial pulse chirp and fiber GVD

The impacts of polarization mode dispersion (PMD) on the pulse-width in linear systems have been investigated. The analytical solutions, including the effects of initial frequency chirp and group velocity dispersion (GVD), are derived. Analyses show that the pulse broadening effects induced by the second-order PMD depend on GVD and chirp parameter, which are different from those induced by the first-order PMD. An initially chirped Gaussian pulse is taken as an example, upon which analytical solutions of rms pulse-width are derived before and after the first-order PMD compensation. The first-order PMD compensator is also evaluated based on these solutions. The results show that the pulse broadening effects will be resisted efficiently by choosing appropriate GVD and chirp parameter; in general, the post-transmission compensation method will be less efficient than the PSP-transmission method.     

高阶PMD统计特性研究

讨论了三阶偏振模色散(PMD)的统计特性及其对于高阶PMD补偿系统的影响.数值模拟结果表明,随着即时差分群时延(DGD)的增加,二阶PMD单位矢量旋转速率的统计覆盖范围的变化趋势与主偏振态(PSP)旋转斜率的相应变化正好相反.此外,随着即时DGD的增加,二阶PMD模值的统计覆盖范围不断增加,使得高速光通信系统中高阶PMD补偿的实现将更加困难.     

Polarization Mode Dispersion in High-Speed Optical Communication Systems

Abstract

We review the research progress concerning some fundamental issues related to polarization-mode dispersion (PMD) in high-speed fiber-optic transmission systems. We pay particular attention to issues such as the PMD-induced pulse broadening, PMD measurement and emulation, as well as PMD compensation. An electrical equalization technique based on a transversal filter and an optical technique based on a nonlinear chirped fiber Bragg gratings for PMD compensation will be discussed.     

A deeper analysis of the second order polarization mode dispersion in optical communications systems

This article presents a new approach to the combined analysis of the first and second-order polarization mode dispersion (SOPMD) and shows their importance in optical communication systems performance. How it affects the relation between second-order polarization mode dispersion (PMD) and the differential group delay (DGD) in a single mode fiber is discussed. The analysis is based on time or wavelength and temperature variations changing/impacting PMD and DGD measured values. We present long term statistical characteristics of second-order PMD over a PMD emulator, and investigate the correlation between SOPMD, depolarization (DEP) and polarization dependent chromatic dispersion (PCD). Some authors calculate these modes from measurements obtained from the first order polarization mode dispersion, assuming a positive correlation between these effects, but this not the real relationship between them. A new interpretation of SOPMD was used to analyze the problem of the spectral stability in terms of the temperature. Actual techniques for determination SOPMD, consequently DEP and PCD, use the variation in time and/or wavelength. In some studies the results obtained for SOPMD are correlated to first-order PMD (FOPMD). This paper shows, based on measurements, that the correlation between first and second order Polarization Mode Dispersion (PMD) in the case where the last one is a function of the temperature can assume positive or negative values.     

Soliton Propagation in Birefringent Fibers

In this article, the propagation of solitons in a single mode fiber with polarization mode dispersion (PMD) is analyzed. In optical fibers, the randomly varying birefringence degrades soliton transmission system in two aspects. First, the dispersive waves cause pulse broadening. Second, the dispersive waves interact with other soliton pulses. Here we studied the effects of PMD on a single pulse and the variation of pulse broadening, energy decay, and degree of polarization on a single soliton pulse propagating over a very long distance.     

单模光纤中的二阶偏振模色散及其统计特性

用琼斯矩阵本征分析法和邦加球法,分别测量了22 km和75 km G.652单模光纤中的二阶偏振模色散,并对其平行分量、垂直分量、PCD（Polarization dependent chromatic dispersion）、消偏振项、各个分量的统计特性及其影响进行了详细的分析,得到了二阶偏振模色散随波长的分布情况及统计特性. 从统计结果可以得到,与PCD项相比,消偏振项在二阶偏振模色散中起主要作用. 该研究对二阶偏振模色散的补偿有一定的指导意义.     

Schemes for complete compensation for polarization mode dispersion up to second order

The required structure and elements of polarization mode dispersion (PMD) compensators for complete second-order compensation are investigated by use of a general PMD vector formalism of concatenated PMD elements based on Mueller matrices and Stokes vectors. The investigation shows that two- and three-stage compensators with five independent parameters can compensate for polarization-dependent chromatic dispersion as well as the depolarization component of second-order PMD.