全光DWDM网络偏振模色散(PMD)分析及其均衡方案

偏振模色散(PMD)已成为长距离高速率数据光网络的主要限制因素.首先分析了偏振模色散产生的机理,然后对偏振模色散建立了理论模型,以此为基础,提出了全光DWDM网络的PMD多通道同时均衡的方案.     

全光DWDM网络偏振模色散分析及其均衡方案

偏振模色散（PMD）已成为长距离高速率数据光网络的主要限制因素。文章首先分析PMD产生的机理,然后建立PMD理论模型,并以此为基础,提出全光DWDM网络的PMD多通道同时均衡的方案。     

全光DWDM网络偏振模色散分析及其均衡方案

偏振模色散（PMD）已成为长距离高速率数据光网络的主要限制因素。文章首先分析了PMD产生的机理，然后对PMD建立了理论模型，以此为基础，提出了全光DWDM网络的PMD多通道同时均衡的方案。     

光副载波复用系统中偏振模色散对偏振度的影响

在光副载波复用系统中若使用偏振度作为偏振模色散的监测信号将会遇到灵敏度低的问题.本文首先讨论了色度色散和初始啁啾对偏振度的影响,然后找出了影响监测信号灵敏度的因素,并提出了相应的解决方法.使用一个窄带滤波器用来平衡光载波和边带的功率,偏振度对偏振模色散的灵敏度将会明显的增长.     

全光DWDM网络偏振模色散分析及其均衡方案

偏振模色散已成为长距离高速率数据光网络的主要限制因素。这里首先分析了偏振模色散产生的机理，然后对偏振模色散建立了理论模型，以此为基础，提出了全光DWDM网络的PMD多通道同时均衡的方案。     

偏振模色散对波分复用系统的影响及补偿方案研究

建立多信道WDM通信系统的PMD理论模型,用数值计算方法可得到了波分复用系统传输的波形,发现PMD对各信道的影响是不同的,为波分复用通信系统中PMD补偿提供理论依据.通过一阶偏振模色散局限性的分析,依据波分复用通信系统中PMD的特点,提出了波分复用通信系统中PMD补偿的最坏信道补偿法,并提出了具体的补偿方案.     

偏振模色散的测试方法

1 引言 随着通信技术的进步,光通信迅速向高速率、大容量和长距离方向发展。在单信道速率不断提高(现已发展到10Gb/s,正向40Gb/s甚至更高发展)的同时,密集波分复用(DWDM)也     

一种新的自适应偏振模色散补偿前馈方法

提出了一种新偏振模色散（PMD）补偿的方法，直接从被补偿光纤中提取偏振色散矢量的大小和方向信息，根据算法调节偏振模色散补偿器的各参量，使得补偿器的快轴与被补偿光纤的慢轴对准，从而使得偏振模色散得到补偿。这种方法的优点是减少了搜索的自由度。建立了40Gb／s偏振模色散前馈补偿系统，并通过数值模拟．对40Gb／s的非归零（NRZ）码的偏振模色散进行了自适应补偿。通过对补偿前后的眼图、偏振度（DOP）和Q值进行对比和分析，结果表明，这种偏振模色散补偿的前馈方法是非常有效的。     

2.5 Gb/s偏振模色散自动补偿对偏振模色散容限值的影响

在我国现有的光纤通信骨干网中,绝大部分速率为2.5 Gb/s。今后如在我国现有的2.5 Gb/s网络系统上进行密集波分复用(DWDM)升级,亦需要考虑偏振模色散(PMD)对系统容量升级的影响。采用十段高双折射光纤级联而成的偏振模色散模拟器模拟实际光纤,从信号中提取基带频率分量作为反馈信号,对2.5 Gb/s系统进行了偏振模色散自动补偿实验,并对反馈前后的系统进行了系统代价的测量和比较。实验结果表明,偏振模色散自动补偿能较大幅度地提高系统的偏振模色散容限值。     

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。     

Distributed polarization-mode dispersion compensation using polarizers

We numerically evaluate the performance of two kinds of distributed polarization-mode dispersion compensation techniques using either linear or elliptic variable polarizers. Each in-line compensator is characterized by only one or two degrees of freedom and the average power is used as a monitor signal, which simplifies the control algorithm. The use of polarizers causes inevitable attenuation of the optical signal, which induces additional noise in amplified systems. Nevertheless, the noise enhancement due to the distributed polarizer-induced loss is shown to be limited in systems operated with erbium-doped fiber amplifiers in gain saturation and the tolerable differential group delay can be improved if the frequency of insertions is increased.     

光纤通信系统新码型用于多信道PMD补偿的研究

根据多信道偏振模色散(PMD)的最坏信道补偿方案,以粒子群优化(PSO)算法作为多信道PMD补偿算法,将一些典型的新型调制格式用于多信道PMD补偿,并以两信道PMD补偿系统为例进行了数值模拟,在补偿最坏信道的同时,保障了其他信道的性能,取得了很好的补偿效果.     

Improved phase delays for optical compensation of polarization-mode dispersion

We present numerical simulations of the average frequency dependence of the differential phase delays (DPDs) that are introduced by polarization-mode dispersion (PMD) between the signal components transmitted in the two principal states of polarization of the fiber. Our study confirms that the first-order approximation of frequency-independent DPDs is valid for fibers that normally do not require PMD compensation. However, for fibers with larger mean differential group delays (DGDs), the first-order approximation tends to overestimate the mean DPDs for any given DGD. Based on our numerical results, we derive closed-form approximations for the frequency and group-delay dependence of the mean DPD conditioned on a given DGD and show that these more accurate DPDs may significantly improve the performance of optical PMD compensators.     

基于光纤差分相移键控的色散补偿方案的研究

为了研究光差分相移键控(DPSK)调制格式在光纤高速传输系统中的色散补偿, 利用色散补偿光纤(DCF)的色散补偿原理, 对40Gbit/s光纤传输系统进行色散补偿, 分析了40Gbit/s单通道光纤传输系统中3种DPSK调制格式信号的频谱特性; 仿真了3种码型的色散容忍度以及3种调制格式在考虑光纤的非线性下的色散补偿方案。结果表明, 光非归零码差分相移键控(NRZ-DPSK)信号具有最好的色散容忍度, 但其受非线性的影响比较大; 33%归零码差分相移键控(33%RZ-DPSK)信号的色散容忍度差, 但其色散补偿后的效果优于NRZ-DPSK; 而载波抑制归零码差分相移键控信号对色散和非线性效应都有较好的抑制; 3种DPSK调制格式均在对称补偿2方案中色散补偿的效果最佳。此仿真研究对光DPSK信号在光纤中的色散补偿具有参考意义。     

色散补偿光纤传输系统的最佳补偿方案

研究了采用色散补偿光纤传输系统的最佳补偿方案,经研究发现,混合补偿方案可以大大减小光纤非线性效应的影响,提高系统传输距离.此外,还对非归零码(NRZ)和归零码(RZ)的传输性能进行了比较.     

Automatic compensation of polarization-mode dispersion for 40 Gb/s transmission systems

We present an automatic compensator that effectively mitigates signal distortion due to polarization-mode dispersion (PMD). Accurate compensation is achieved by utilizing a degree of polarization (DOP) monitor with a measurement uncertainty of better than 1% achieved by applying a self-dependent precalibration procedure. The compensation performance at 43 Gb/s was evaluated systematically with respect to both first- and second-order PMD by using a crystal-optical PMD emulator. The compensator extended the tolerable differential group-delay (DGD) limit from 8 to 28 ps, while maintaining the Q penalty below 1 dB. In terms of the average of a Maxwellian-distributed DGD, the PMD compensator enabled transmission for up to 8 ps, or about three times higher than the level tolerated in the uncompensated case. In addition to the compensation performance, we demonstrate successful operation, even for distorted signals with high chromatic dispersion. We believe this capability will be a key enabler for a combined operation with adaptive chromatic dispersion compensators.     

Importance sampling for polarization-mode dispersion

We describe the application of importance sampling to Monte-Carlo simulations of polarization-mode dispersion (PMD) in optical fibers. The method allows rare differential group delay (DGD) events to be simulated much more efficiently than with standard Monte-Carlo methods and, thus, it can be used to assess PMD-induced system outage probabilities at realistic bit-error rates. We demonstrate the technique by accurately calculating the tails of the DGD probability distribution with a relatively small number of Monte-Carlo trials     

Fibers with low polarization-mode dispersion

Fibers with low polarization-mode dispersion (PMD) enable high-bit-rate time-division-multiplexed optical communication systems. These fibers are becoming increasingly important with the growing implementation of wavelength-division-multiplexing (WDM) transmission with channel bit rates of 40 Gb/s. Important to the realization of low PMD fibers are the fiber's index and stress profiles, polarization-mode coupling, and the evolution of the polarization state with length. This paper reviews recent progress in the understanding of the fabrication and characteristics of these fibers. The paper also discusses the important fiber physical parameters, including the fiber index profile and fiber spinning parameters and their impacts on the realization of low PMD performance.     

Planar lightwave circuit polarization-mode dispersion compensator

In this letter, we fabricated an integrated polarization-mode dispersion compensator on a silica-based planar lightwave circuit that incorporated an endless polarization controller and a fixed polarization dependent delay line. The compensator consisted of polarization beam splitters, thermooptic phase shifters, tunable couplers, and polarization converters. We experimentally confirmed its operation at a data rate of 43 Gb/s     

Impact of chirping on polarization-mode dispersion compensated systems

Investigates the effect of chirp, resulting from either the transmitter, chromatic dispersion, or Kerr effect in the fiber, on polarization-mode dispersion (PMD) compensated systems. We demonstrate both experimentally and numerically the deleterious impact of chirping on systems with first-order PMD compensation. We present a way to optimize the PMD compensator performance by minimizing the total chirp of the signal at the receiver side.