Polarization Mode Dispersion of Installed Fibers

Polarization mode dispersion (PMD), a potentially limiting impairment in high-speed long-distance fiber-optic communication systems, refers to the distortion of propagating optical pulses due to random birefringences in an optical system. Because these perturbations (which can be introduced through manufacturing imperfections, cabling stresses, installation procedures, and environmental sensitivities of fiber and other in-line components) are unknowable and continually changing, PMD is unique among optical impairments. This makes PMD both a fascinating research subject and potentially one of the most challenging technical obstacles for future optoelectronic transmission. Mitigation and compensation techniques, proper emulation, and accurate prediction of PMD-induced outage probabilities critically depend on the understanding and modeling of the statistics of PMD in installed links. Using extensive data on buried fibers used in long-haul high-speed links, the authors discuss the proposition that most of the temporal PMD changes that are observed in installed routes arise primarily from a relatively small number of "hot spots" along the route that are exposed to the ambient environment, whereas the buried shielded sections remain largely stable for month-long time periods. It follows that the temporal variations of the differential group delay for any given channel constitute a distinct statistical distribution with its own channel-specific mean value. The impact of these observations on outage statistics is analyzed, and the implications for future optoelectronic fiber-based transmission are discussed     

Polarization Mode Dispersion in Distributed Erbium-Doped Fibers

In the design of distributed erbium-doped fibers (DEDFs) for ultra-high bit-rate ( > 40 Gbit/s) soliton transmission, polarization mode dispersion (PMD) is an important design parameter. We have measured the PMD values of DEDFs from two different sources and found them to be an order of magnitude higher than those suitable for ≥ 40 Gbit/s soliton transmission. Theoretical modeling and microscopic inspection of fiber core ellipticity have been carried out to understand the high PMD values in these DEDFs. It is believed that core ellipticity and erbium doping process-induced stress are the main reasons for the high PMD values in these fibers. This highlights an important design and fabrication problem which must be solved before DEDFs can fulfil their promise as a channel for long-haul ultra-high bit-rate soliton transmission.     

单模光纤中的偏振模色散(PMD)

从起因、定义和统计特性等方面对单模光纤中的偏振模色散现象做了简要介绍。     

Polarization Mode Dispersion Management Using Unidirectionally Spun Fibers

Optical fiber links made by concatenating unidirectionally spun fibers with alternate helicities are considered. The polarization mode dispersion of such links is thoroughly analyzed, and it is shown that with a proper design of the link, substantial differential group delay (DGD) reduction can be achieved. In particular, the highest performance is attained when a well-defined balance condition is satisfied. By relaxing this condition, a tradeoff between the complexity of the link structure and the DGD reduction can be achieved as well     

单模光纤中偏振模色散测量方法的研究

比较了单模光纤中常见的几种线性偏振模色散(PMD)的测量方法,重点讨论了两种最新提出的非线性PMD测量方法,详细分析并指出了每种测量方法的优缺点、测量中应该注意的问题和它们的适用范围.     

温度对单模光纤偏振模色散的影响研究

随着光纤通信系统传输容量的不断发展 ,光纤中的偏振模色散 PMD成为限制高速光纤通信系统传输容量的极限因素。偏振模色散是由于光纤结构的不完善性或者受到外界应力的作用而产生的 ,因此偏振模色散受外界环境因素的影响较大。许多研究表明偏振模色散对温度具有较强的敏感性 ,是温度的函数。采用波长扫描法就温度对单模光纤偏振模色散的影响展开研究 ,研究结果表明 ,单模光纤偏振模色散将随着温度的升高而呈现减小的趋势     

单模光纤偏振模色散(PMD)的理论

系统地研究了有关偏振模色散（ＰＭＤ）的一些理论,包括ＰＭＤ的起因、估算、模式耦合、标称值的确定等。指出了双折射是引起ＰＭＤ的首要原因,说明了光纤材料的形状、应力、弯曲、扭转及电磁场等因素都能导致双折射。而模式耦合则是影响ＰＭＤ的一系列特性（例如ＰＭＤ与长度的依赖关系等）的重要原因。文中还提出了确定ＰＭＤ标称值的建议方法     

测量偏振模色散的新方法

介绍了用偏分孤子法对偏振模色散测量的实验原理和实验系统,对实验结果进行了分析,表明,偏分孤子法是一种新的可选偏振模色散测量方案。     

通信光纤及光子晶体光纤偏振模式色散的测量方法

从基本原理、系统配置和优缺点等方面系统阐述了国际电工委员会规定的四种标准偏振模色散测量方法—琼斯矩阵本征分析法、波长扫描计算法、波长扫描傅立叶变换法和干涉法,并进行了比较和分析。通过对大模场光子晶体光纤偏振模色散特性分析,说明了针对普通单模光纤制订的标准测量方法可应用于新型光子晶体光纤的PMD测量。     

偏振模色散补偿系统

以偏振主态原理为基础,利用高双折射光纤作为PMD补偿器,在实验上实现了0－50ps的偏振模色散补偿。这对于长距离,10Gbit/s以上的光通信系统具有重要的实际意义。     

用光谱分析法测量单模光纤的偏振模色散

本文介绍了光谱分析法测量单模光纤偏振模色散（ＰＭＤ）的理论根据和测试实验装置以及实测结果。由于目前单模光纤偏振模色散测试仪表价格昂贵,所以本文介绍的方法很有实用价值。     

色散、偏振模色散和非线性

本介绍了光纤的色散和偏振模色散，及其对系统的影响，介绍了两种主要的色散补偿的方法；分析了在密集波分复用(DWDM)系统中，光纤的各种非线性效应及对系统性能的影响。     

偏振模色散对单模光纤的影响

单模光纤的偏振模色散是两个相互正交偏振模之间的差分群时延 ,是高速率数字系统性能的限制因素之一 ,我们必须深刻理解偏振模色散的理论 ,才能在施工时采取相应的措施 ,保证光纤系统的施工质量     

基于不同的非线性前色散补偿技术的比较

对非线性前色散补偿系统中的完全补偿、过补偿和欠补偿进行了数值模拟。数值结论表明：采用非线性前补偿不论是完全补偿、过补偿还是欠补偿，当入纤平均功率为1mW至15mW时20Gbit／s、最大半宽度为20ps的RZ脉冲经过100km的标准单模光纤后均能满足误码率小于10－9的要求。当入纤功率较大时，采用完全补偿经过一个放大距离后Q值最大，而且能够传输的放大周期也最多。     

偏振模色散的分析模型

当光纤通信系统单信道速率到40Gbit/s以上时，偏振模色散的影响已经成为严重影响系统性能的主要因素。对偏振模色散现象的研究通常可采用几种不同的分析模型：琼斯矩阵、斯托克斯空间、耦合非线性薛定谔方程；对这几种分析模型作了详细地介绍，进行了分析和比较，并对40Gbit／s光纤传输系统进行了数值模拟。     

偏振模色散的抑制技术

当光纤通信系统单信道速率升级到40 Gbit/s以上时,偏振模色散(PMD)已经成为严重影响系统性能的主要因素.PMD是由于光纤结构的不完美性以及外界应力作用而产生的,是一个服从Maxwell分布的随机量.文中对现有的PMD抑制技术进行了分析评价,并针对波分复用系统中PMD的补偿提出了可行性的方案.     

光纤偏振模色散测试仪

论述了测试仪所采用的光谱分析法光纤偏振模色散测试原理,介绍了弱导模光纤中偏振模色散的随机特性以及变化规律,并给出了光纤偏振模色散测试仪的测试结果。     

低偏振模色散和负色散斜率的色散补偿光纤的研制

从理论上对三包层的负色散斜率的色散补偿光纤进行了研究，分析了该光纤的各个参量对色散曲线的调节作用；采用在光纤拉丝过程中同时旋转预制棒的工艺来增强模耦合，实现了光纤偏振模色散的减小；并改进国内已有的改进的化学汽相沉积（ＭＣＶＤ）工艺研制出了国内较高水平的色散补偿光纤。同时发现色散补偿光纤只有在一定范围内的拉丝芯径内，靠牺牲大负色散数值才能获得大负色散斜率。     

Digital Equalization of Chromatic Dispersion and Polarization Mode Dispersion

In this paper, we consider a fractionally spaced equalizer (FSE) for electronic compensation of chromatic dispersion (CD) and polarization-mode dispersion (PMD) in a dually polarized (polarization-multiplexed) coherent optical communications system. Our results show that the FSE can compensate any arbitrary amount of CD and first-order PMD distortion, provided that the oversampling rate is at least 3/2 and that a sufficient number of equalizer taps are used. In contrast, the amount of CD and PMD that can be corrected by a symbol-rate equalizer only approaches an asymptotic limit, and increasing the number of taps has no effect on performance due to aliasing that causes signal cancellation and noise enhancement.     

参量效应在零色散波长附近的位相匹配

研究了几种掺杂情况下光纤折射率的变化导致光纤零色散波长的变化，提出一种用于参量过程中位相匹配的数值分析方法，对光纤中材料色散与波导色散引起的参量过程中的位相失配进行了数值分析，给出相应的随泵浦波长和泵浦与信号间的频移而变化的位相失配空间曲面，结果表明，在零色散波长附近有最大的频移可满足位相匹配，且此规律不随零色散波长移动而发生变化