High-speed polarization mode dispersion compensation in a 43-Gb/s RZ-DQPSK transmission system over 1200 km of standard single-mode fibre

This paper reports that the designed optical polarization mode dispersion compensator shows a good performance under the real-time variation of differential group delay, state of polarization and principal state of polarization in a （40×43）-Gb/s dense-wavelength-multiplexing, 1200-km enhanced return-to-zero differential-quadrature-phase-shift- keying （RZ-DQPSK） system. The polarization mode dispersion tolerance of the system is improved by 26 ps using the optical polarization mode dispersion compensator. The short and long time stabilities are tested with the bit error ratio recorded.

PSO-based Control Algorithm for Polarization Mode Dispersion Self-adaptive Compensation

Polarization mode dispersion(PMD) is considered to be the ultimate limitation in high-speed optical fiber communication systems. Establishing an effective control algorithm for adaptive PMD compensation is a challenging task, because PMD possesses the time-varying and statistical properties. The particle swarm optimization(PSO) algorithm is introduced into self-adaptive PMD compensation as feedback control algorithm. The experiment results show that PSO-based control algorithm has some unique features of rapid convergence to the global optimum without being trapped in local sub-optima and good robustness to noise in the optical fiber transmission line that has never been achieved in PMD compensation before.

Multichannel Adaptive Polarization Mode Dispersion Compensation with One Compensator in Dense Wavelength Division Multiplexing Transmission Systems

A simple two-section polarization mode dispersion(PMD) compensator is proposed for multichannel PMD compensation, which can compensate two or even more channels simultaneously. Because of the statistical characteristics and the frequency-dependence of PMD, for current single mode fiber with moderate PMD, the probability that all channels are severely degraded at the same time is extremely small, which makes it possible to compensate a dense wavelength division multiplexing(DWDM) transmission system with moderate PMD using this compensator. It is shown that the outage probability of a 40×43 Gb/s DWDM transmission system using this compensator is decreased significantly from 3.6×10-3 to 3.6×10-5.

A theoretical and experimental study on all-normal-dispersion Yb-doped mode-locked fiber lasers

We report on a theoretical and experimental study of an all-normal-dispersion （ANDi） Yb-doped mode-locked fiber laser, in which nonlinear polarization rotation （NPR） is used to realize mode-locking without any dispersion compensation. Based on the coupled nonlinear Schr6dinger （CNLS） equation, a model simulating the mode-locked process of an all-normal-dispersion ring fiber laser is developed, which shows that the achievement of stable mode-locking depends on the alignment of the polarization controller （PC） along the fast-polarization axis of the fiber, the birefringence intensity, and the net cavity dispersion. According to the theoretical analysis, stable mode-locked pulses with pulse duration 300 ps and average output power 33.9 mW at repetition rate 36 MHz are obtained.

The Effect of Polarization Mode Dispersion on the Transmission System Using Dispersion Compensation Fiber

In this paper, we simulate the effect of Polarization Mode Dispersion( PMD ) on 40 Gb/s dispersion compensation transmission system by resolving the coupled nonlinear Schrodinger equation, and calculate the performance of system with different duty cycle order and chirp of the super Gaussian pulse. The results show that the performance of the system changes with these parameters, and there is a group of optimum parameters for the optimum performance of the system.

A novel tunable polarization mode dispersion compensator with strain chirped fiber Bragg gratings

A tunable polarization mode dispersion (PMD) compensator based on strain-ckirped fiber Bragg gratings (FBGs) is proposed. It natures in flexible designing, large tuning range, without using linear or nonlinear chirped phase mask, fast tuning response time, continuously adjustable, all-fiber based, compact, and cheap.

Impact of polarization mode dispersion and nonlinearities on 2-channel DWDM chaotic communication systems

This paper has designed 2-channel dense wavelength division multiplexing （DWDM） chaotic sys- tem at the frequencies of 193.1 and 193,2THz, respec- tively. The optical chaotic signals were produced by using the semiconductor laser that is numerically modeled by employing laser rate equations. These two channels were multiplexed and then propagated through single mode optical fiber （SMF） of 80kin length with dispersion compensating fiber of 16 km length. Erbium doped fiber amplifier （EDFA） was used to compensate the power losses in the SMF. In lhis paper, we investigated the effects of polarization mode dispersion （PMD） and nonlinearities especially stimulated Raman scattering （SRS） on 2 channel DWDM chaotic communication system by varying the length of the SMF and value of differential group delay （DGD）.

Generation of DQPSK format and its performance against polarization mode dispersion

We propose a novel transmitter and receiver for differential quadrature phase-shift keying （DQPSK） format. The impact of the first-order polarization mode dispersion （PMD） on systems using DQPSK with 100- Gb/s non-return-to-zero （NRZ） or return-to-zero （RZ） format is investigated. Through computing the eye openings of DQPSK formats under different PMD conditions, it is found that NRZ DQPSK, as compared with RZ DQPSK, incurs smaller eye opening due to PMD. Carrier-suppressed return-to-zero （CSRZ） DQPSK format has better tolerance than RZ DQPSK format to PMD for a given bit rate.

10Gb/s光通信传输系统中一阶PMD自适应补偿实验

在 10Gb/s归零码 (RZ)光通信传输链路中成功地搭建一阶PMD自适应补偿的实验系统 ,补偿量 2 9ps ,跟踪补偿时间在 1s以内 。

Polarization Mode Dispersion Probability Distribution for Arbitrary Mode Coupling

The probability distribution of the differential group delay for arbitrary mode coupling is simulated with Monte-Carlo method. Fitting the simulation results, we obtain probability distribution function for arbitrary mode coupling.

Filter control polarization mode dispersion in dispersion managed soliton systems

In this paper, the dispersion managed soliton (DMS) transmission equation is built on considering the effects of polarization mode dispersion (PMD) and filter control. The DMS transmission of filtering control in constant birefringence fibers is firstly analyzed by varitional method, from which the evolving rules of characteristical DMS parameters are obtained. Secondly, the stability of DMS transmission and its timing jitter are investigated in the random varying birefringence fibers with the conventional model of PMD. The results reveal that filter control DMS system has powerful robustness to PMD effects and DMS's timing jitter can be decreased considerably with the help of filters.

高速传输系统中高阶PMD的影响

研究由于偏振模色散 (PMD)引起的时域脉冲响应 从传输矩阵的角度分析了包含各阶与频率相关的差分相时延 (DPD)、主偏振态 (PSP)对脉冲波形的影响 ,并通过仿真结果验证理论的有效性 同时 ,也分析了PMD对系统带来的眼图代价 ,对

基于DSP的PMD补偿逻辑控制模块的实现

国内首次对偏振模色散(PMD)自适应补偿系统中逻辑控制部分进行了集成化设计,详细介绍了系统的硬件结构、软件及工作流程。详细设计了PSO算法模块在DSP系统中的实现,将该DSP系统应用到二阶PMD自适应补偿系统中进行验证,结果表明,设计的DSP逻辑控制模块对一阶及二阶PMD补偿效果很好。

一种融合改进TF-IDF与词典模型的情感分类算法

针对传统情感文本分类算法存在情感特征词的极性偏好区分度较低和稳定性较差等问题,提出了一种改进词频-逆文本频率(TF-IDF)模型与词典模型相融合的情感文本分类算法。首先,通过情感特征词在不同情感类型语料中的频率分布和离散系数,度量情感特征词极性偏好所包含的区分度和稳定性,生成情感特征词极性指标;然后,使用该指标改进TF-IDF模型的情感特征词权重;最后,基于改进的TF-IDF模型,使用带决策函数的有监督分类算法计算情感文本的极性得分,并与词典模型所得的极性得分进行调和平均,得到情感文本综合极性得分。

高速光纤通信系统中PMD的补偿技术

简要介绍了目前存在的几种 PMD补偿技术 ,分析了各种补偿技术的优缺点 ,指出了当前 PMD补偿所面临的问题。

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。

基于DOP反馈的10Gb/s系统PMD自适应补偿实验

报道了基于DOP反馈的10Gb/sNRZ码和RZ码光通信系统的PMD自适应补偿实验,自适应补偿器的搜索时间低于1s,受到突然扰动后的恢复时间少于20ms。

一种简单实用低插损的PMD模拟器

采用偏振控制器级联保偏光纤的方案 ,数值模拟了偏振模色散模拟器的统计分布。通过一种优化算法 ,采用特定长度的 10段高双折射率光纤 ,使级联而成PMD模拟器的偏振模色散统计分布接近于麦克斯韦分布。实验测量结果表明 ,这种模拟器插损低 ,可控性好 ,变化迅速 ,DGD分布符合麦克斯韦分布。

以啁啾光纤光栅为补偿器的自适应PMD补偿的实验研究

基于光信号偏振度(DOP)与光纤链路差分群时延(DGD)良好单调关系,提取光信号的DOP作为监测信号,通过搜索运算控制偏振模色散(PMD)补偿器,找到链路中DOP达到最大值时补偿器的状态,从而实现一阶PMD的补偿.采用等效啁啾技术,用具有光敏性质的保偏光纤制成啁啾光纤光栅,将其作为PMD补偿器中的时延线,完成了10Gbit/s、NRZ码光纤通信系统的自适应PMD补偿的实验研究.在自适应PMD补偿的控制算法中,使用了粒子群最优化(PSO)的人工智能搜索法,它具有快速搜索到全局最大值、不易陷入局部极大、抗噪声等特点.实验结果显示,以双折射啁啾光纤光栅为补偿器的自适应PMD补偿系统具有良好的补偿效果.