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     

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。     

基于偏振模色散矢量的偏振模色散补偿方案的研究

在研究局部偏振模色散矢量与整体偏振模色散矢量关系的基础上，从理论上得到完全补偿偏振模色散的关系，结论是至少利用两段保偏光纤才能完全补偿。提出了基于偏振模色散矢量的偏振模色散补偿方案和调节控制的算法原理及改进的方向。这些结果对正确进行偏振模色散补偿是很有帮助的。     

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。     

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。     

能够补偿二阶偏振模色散的三阶段偏振模色散补偿器

简要分析了偏振相关色散对光通信系统性能的影响,提出了一种三阶段高阶偏振模色散补偿方案,从理论上分析了它同时补偿偏振相关色散和偏振主态旋转的可能性,并提出了其可能存在的两种工作方式.通过数值模拟与两阶段补偿方案进行了性能比较,其偏振模色散容限比两阶段补偿提高约17%个比特周期 关键词： 光通信 光偏振 光纤色散     

偏振模色散影响色散控制孤子传输的理论研究

采用变分法分析高速色散控制孤子在双折射光纤中的传输规律。首先建立了色散控制孤子在双折射光纤中的扰动传输模型 ,然后解析了偏振模色散影响下色散控制孤子各参量的传输演化规律 ,最后对解析结果进行了计算。研究结果表明 ,偏振模色散参量对色散控制孤子能量、脉宽的演化影响很大 ,当偏振模色散很大时 ,如Dp>0 .3ps/km1/ 2 时 ,必须考虑采用某些在线控制手段来有效抑制偏振模色散对传输系统的影响 ,然而 ,当Dp≤ 0 .1ps/km1/ 2 时 ,系统几乎不受影响 ,同时本文还证明了色散控制孤子抗偏振模色散扰动的能力强的这一特点。为研究偏振模色散对高速非线性传输系统、特别是色散控制孤子传输系统的影响提供了理论依据和研究方法。     

双折射光纤中偏振模色散的抑制

利用双折射光纤中孤子自捕获现象可以抑制偏振模色散,但这种抑制技术对传输参量有严格的限制.本文提出在双折射光纤中周期性地改变快慢轴的方法来抑制偏振模色散. 研究发现,这种方法在一定程度上能有效地抑制偏振模色散,并且光纤间偏振轴的夹角偏差有利于对偏振模色散的进一步抑制.     

强双折射光纤中色散效应对偏振模传输的影响

本文研究了在强双折射光纤中色散效应对偏振模传输的影响.发现当二阶色散系数较大时,偏振模能稳定传输,但所需入纤功率较高;当降低二阶色散影响以降低对光源要求时,三阶色散对偏振模长距离传输起破坏作用,三阶色散参量越大,对偏振模的破坏也越大.     

10 Gb/s光纤通信系统一阶偏振模色散动态补偿系统反馈控制的实现

在偏振模色散(PMD)自动补偿技术中,如何根据反馈信号得到相应的控制信号,使补偿速度跟随偏振模色散变化始终是该技术的一个核心问题。提出了一种新颖的自适应抖动跟踪算法,完成了以微波信号为反馈的多自由度的一阶偏振模色散自动反馈补偿系统的跟踪补偿实验。算法成功地解决了传统算法在跟踪搜索过程中易陷入局部极值的问题,有效地克服了系统中的重要控制器件偏振控制器的磁滞现象以及动态补偿时跟踪搜索过程中易出现的瞬间恶化现象。实验结果表明该算法在对出现突发偏振模色散扰动后自动进行补偿的响应速度在ms量级,最快能达到1~2 ms。     

Compensating Large PMD by Four Free degrees in an OTDM System

In this paper, by introducing a two-stages polarization mode dispersion (PMD) compensator after a optical fiber link with a large PMD, we compensated over 270ps first-order and 2000ps2 high-order PMD in a optical fiber link with super high PMD. Our experimental results shows that, the compensators based on the two-stages of compensator can be used to PMD compensation in a 20Gb/s OTDM system with 60 km high PMD fiber. Before compensation,270ps DGD is became into max. 7ps after compensation. At simultaneity, the tunable FBG have a function of dispersion compensation.     

Compensating large PMD by a fiber grating

In this paper, the first- and second-order polarization mode dispersion (PMD) with the amount of 132.994-ps differential group-delay (DGD) and maximum 476.129-ps/nm second-order PMD can be compensated by a two-stages PMD compensator at a 40-Gb/s optical fiber communication system. The first stage has one free degree that is used for first order and high orders PMD compensations by rotating the state of polarization. The second-stage is used for remainder PMD compensations. After compensation, the average DGD and the maximum second-order PMD are reduced to 345.310 fs and 3.102 ps/nm, respectively.     

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.     

Polarization Mode Dispersion in High-Speed Optical Communication Systems

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.     

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.     

The effect of variable PSP angles in a PMD compensator

A polarization mode dispersion compensator (PMDC) composed of two polarization mode dispersion (PMD) elements and one polarization dependent loss (PDL) element is proposed. Simulation shows that, due to the variable angle between the two principal states of polarization (PSPs) of the compensator, the proposed compensator can improve the PMD compensation efficiency for systems with both PMD and PDL, especially when higher order PMD is compensated.     

Two-stage adaptive PMD compensation in 40-Gb/s OTDM optical communication system

An experiment of two-stage adaptive compensation for polarization mode dispersion (PMD) in a 40-Gb/s optical time-division multiplexed communication system is reported. The PMD monitoring technique based on degree of polarization was adopted. The particle swarm optimization (PSO) algorithm was introduced in adaptive PMD compensation. The comparison was made to estimate the effectiveness between PSO algorithms with global neighborhood structure (GPSO) and with local neighborhood structure (LPSO).The LPSO algorithm is shown to be more effective to search global optimum for PMD compensation than GPSO algorithm. The two-stage PMD compensator is shown to be effective for both first- and second order PMD, and the compensator is shown to be bit rate independent. The optimum searching time is within one hundred milliseconds.     

Dynamic PMD compensation in 40-Gb/s optical communication system

A 40-Gb/s optical time division multiplexing (OTDM) return-to-zero (RZ) transmission experiments in cluding a dynamic polarization mode dispersion (PMD) compensation was reported. The dynamic PMD compensator is made up of two-stage four degrees of freedom (DOF). The first stage adopts polarization controller and fixed time-delayed line. The second stage is variable differential group delay (DGD) element. The PMD monitoring technique is based on degree of polarization (DOP) as error signal. A novel practical adaptive optimization algorithm was introduced in dynamic adaptive PMD compensation. The experimental results show that the performance of the PMD compensator is excellent for 40-Gb/s RZ transmission systems with the large DGD. With this compensator, a significant improvement of system performance can be achieved in the eye pattern of a received signal. The first-order compensating ability of the compensator is greater than 30 ps. The second-order compensating ability is greater than 200 ps2.The first-order optimum compensating time is within 10 ms. The second-order optimum compensating time is within 24 ms.     

Polarization mode dispersion and chromatic dispersion compensation by using a three-stage compensator

A three-stage compensator used for Polarization mode dispersion (PMD) and Chromatic dispersion (CD) compensation is proposed. The compensator is capable of compensating the two components of second-order PMD when no CD exists. Two operating points of compensating second-order PMD have been proposed. Two-stage and three-stage compensators are compared by the outage probability. When CD is introduced, the compensator should retain a quantity of second-order PMD to compensate CD. The outage probability when PMD and CD coexist has been calculated. The results show that a tradeoff must be made in order to compensate CD and PMD at the same time.     

PMD compensation techniques

Mitigating PMD is still a challenge in todays optical communications. After giving the key performance indicators dictated by the statistical nature of PMD, we introduce the classification of PMD compensation schemes into 2 categories: optical and electrical PMD compensators. In a first part, we explain the operation principle of a PMD compensator by taking a detailed look at the basic optical PMD compensator and appropriate feedback signals. More complex multistage structures and a feed-forward adaptation approach are also discussed. This first part is closed by results from a one-year field trial confirming the behavior and performance of a prototype compensator. In the second part of this article, electronic equalization for PMD mitigation is explained. Starting with a discussion on performance and adaptation of linear equalizers suitable for analog electronic signal processing, finally also the Viterbi equalizer basing on digital signal processing is analyzed. A comparative review of mitigation by optical or electronic means concludes the discussion.