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

An experiment of two-stage adaptive compensation for polarization mode dispersion (PMD) in a 40 Gb/s optical time-division multiplexed (OTDM) communication system is reported. The PMD monitoring technique based on degree of polarization (DOP) 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 ability of tracking changed PMD using PSO algorithm was also investigated. 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 several hundreds of milliseconds. The response time for recovery from a sharp disturbance is about 11 ms.     

粒子群优化算法在自适应偏振模色散补偿中的性能研究

反馈控制算法是偏振模色散的自适应补偿器的关键组成部分,将粒子群优化算法(PSO)引入到偏振模色散自适应补偿系统中。该算法的优点是具有快速收敛到全局最佳值的能力、避免搜索陷入局部极值的能力、抗噪声能力和多自由度控制能力。理论上分析了粒子群优化算法的两个分类———全局邻居结构粒子群优化(GPSO)和局部邻居结构粒子群优化(LPSO)在搜索全局最佳值方面的能力优劣,给出了局部邻居结构粒子群优化算法成功率达100%的三种邻居拓扑结构。实验表明:在补偿一阶偏振模色散时,全局邻居结构和局部邻居结构搜索全局最佳的成功率都能满足要求,全局邻居结构算法收敛速度快。而在补偿二阶偏振模色散时,全局邻居结构成功率降低,而局部邻居结构仍可以满足要求。     

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.     

动态偏振模色散补偿的自适应算法及实现

基于研制成功的两级偏振模色散自适应补偿系统,提出对光传输系统中偏振模色散(PMD)自动搜索跟踪的补偿算法,该算法解决了偏振模色散补偿多自由度搜索中易于陷入局部极大值的问题.实验证明应用该算法制成的偏振模色散自适应补偿器性能优越,所能达到的性能参数为：全局补偿搜索时间78.77 ms,跟踪响应时间15.75 ms.另外,为了将研制的动态PMD补偿器得以实用化,就PMD补偿系统中的核心——取样反馈控制模块的性能进行了剖析.     

Two-stage adaptive PMD compensation experiment for 10-Gb/s optical communication system

We report the adaptive compensation experiment of polarization mode dispersion (PMD) for 10-Gb/s non return-to-zero (NRZ) and return-to-zero (RZ) optical communication systems using a two-stage PMD compensator and the monitoring technique based on degree of polarization (DOP) feedback-signals. The DOP monitor has its advantages of bit-rate independent and modulation format independent. The two-stage compensator has the capacity of compensation for the first- and second-order PMD. The compensated differential group delay (DGD) is up to 80 ps, and compensated principal state of polarization rotation rate is 20 ps. The time used for compensation is less than 1 second.     

40 Gb/s光时分复用系统中两级偏振模色散自适应补偿实验研究

偏振模色散效应严重制约着长距离高速光纤通信的发展,偏振模色散的自适应补偿成为光通信领域研究的焦点。利用两阶段偏振模色散补偿器,采用6个自由度的粒子群优化算法(PSO),通过在线监测搜索光纤链路信号的偏振度极值作为反馈控制信息,在40Gb／s归零码高速光纤传输链路中成功实现了ms量级的偏振模色散自适应补偿。补偿前后采用庞加莱球法测量光纤链路中偏振模色散量,测量结果表明在信号中心波长1560．5nm处,差分群时延补偿前后测量值分别为21ps和1．3ps,而二阶偏振模色散补偿前后测量值分别为266ps^2和43．5ps^2。补偿后实验链路中的一阶和二阶的偏振模色散同时得到不同程度的补偿,并且系统的总的功率代价在误码率为10^-9时小于1dB。     

40Gbit/sOTDM系统中二阶偏振模色散自适应补偿技术研究

报导了一个40 Gbit/s OTDM系统中二阶偏振模色散(PMD)自适应补偿系统,此实验系统基于偏振度的反馈控制方法实现了二阶偏振模色散自动补偿.在中心波长1560.5 nm处,补偿后的DGD和二阶PMD效应改善明显.采用粒子群优化算法作为偏振模色散自适应补偿的搜索算法,补偿时间30 ms左右.     

Study on application of local neighborhood artificial fish swarm algorithm for 40?Gb/s adaptive second-order polarization mode dispersion compensation

Based on a newly improved artificial fish swarm algorithm– local neighborhood artificial fish swarm algorithm (LNAFSA), we studied its application for adaptive polarization mode dispersion (PMD) compensation. In the adopted local neighborhood structure, each artificial fish only communicated with other five neighboring artificial fishes. Under a simulated 40?Gb/s adaptive second-order PMD compensation for non-return- to-zero and carrier-suppressed return-to-zero formats, the study demonstrated the effectiveness of LNAFSA. In a defined searching process, the eye diagrams showed that the algorithm resulted in an effective compensation effect and produced the maximum consuming time within 300?ms. Much better performance than simplex algorithm and genetic algorithm was also observed. In tracking process, LNAFSA achieved the goal of compensation in about 14?ms.     

基于PSO算法的WDM系统中自适应PMD补偿的性能分析

提出了一种应用于WDM系统中的自适应偏振模色散(PMD)补偿方法。将偏振扰频器与基本正交偏振分束探测相结合,首先由偏振信号光功率PS和消偏的背景噪声PN得到光信噪比(OSNR),然后再通过OSNR与偏振度(DOP)的关系来实现多信道DOP的监测。采用粒子群优化(PSO)算法实现了DOP的搜索和跟踪,并经D/A转换,将对应的电压施加在偏振控制器上。调制电压范围为0~10V,调节信号的基本偏振态,从而形成闭环反馈控制模块。通过多次迭代,得到了DOP的最佳值,实现了对PMD的自适应补偿。补偿后,眼图张开度得到了明显的改善。论证了补偿方法的有效性。     

光纤偏振模色散对信号偏振度的影响

采用一种简化的线路传输模型，详细讨论了在高速光纤通信系统中，线路偏振模色散（PMD ），尤其是二阶PMD、输入信号偏振态等对信号偏振度（DOP）的影响，并指出以信号DOP做 反馈控制信号适合于一阶PMD优化补偿系统，但在较大二阶PMD的影响下，将增加控制算法的 复杂性，使系统可能陷入局部最优解. 关键词： 信号偏振度 偏振模色散 信号偏振态     

4×10Gb/s OTDM系统中偏振模色散自适应补偿的研究

利用信号偏振度为反馈信号，基于可变步长最大值搜索算法实现了4×10?Gb/s 光时分复用 （OTDM）系统偏振模色散（PMD）自适应跟踪补偿实验.PMD补偿器为偏振控制器加可变时延 线的四自由度结构.最大差分群时延（DGD）补偿量为25?ps，即信号的一个比特周期，补偿 时间小于50?ms. 关键词： 偏振模色散 光时分复用系统 偏振度 自适应补偿     

Adaptive PMD Compensation in 10 Gbit/s RZ Optical Communication System

We report an experiment of adaptive compensation for polarization mode dispersion (PMD) in 10Gbit/s return zero (RZ) optical communication system. The quasi-real-time PMD compensation is realized. The algorithm so-called particle swarm optimization (PSO) is used to control feedback compensation system.     

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。     

New control algorithm for automatic PMD compensation system

A new cross-tracking method is proposed to improve the convergent speed of the control algorithm in real-time polarization mode dispersion（PMD）compensation systems.The cross-tracking algorithm is compared with the previously used dithering particle swarm optimization（DPSO）and gradient particle swarm optimization（GPSO）algorithms,and it is proven to offer the best performance among the three algorithms.The transmission of a 43-Gb/s differential quadrature phase-shift keying（DQPSK）signal over a 1 200-km fiber span using a compensator based on digital signal processing（DSP）is demonstrated via the cross-tracking algorithm.     

光纤通信系统中偏振模色散自适应补偿实验研究

成功地研制了光纤通信系统偏振模色散的自适应补偿实验系统.实验中采用特定频率分量功率取样作为反馈信号,采用一种名为PSO(Particle Swarm Optimization)的优化方法作为反馈控制算法.偏振模色散的补偿量达30 ps,自动跟踪补偿时间为1～2 s,实现了准实时自动跟踪补偿.     

An experiment of PMD compensation in 40-Gb/s PSBT transmission system

An adaptive polarization mode dispersion （PMD） compensation experiment is reported in a 40-Gb/s phase shaped binary transmission （PSBT） communication system, with the use of a new digital signal processor （DSP）-based optical PMD compensator. PMD tolerance is found to be enhanced by 8 ps after PMD compensation with 1-dB optical signal-to-noise ratio （OSNR） penalty. Under the condition of fast change of states of polarization up to 85 rad/s in the fiber link, the performance of our PMD compensator undergoes the bit error ratio （BER） test for as long as 10 h.     

Adaptive PMD compensation in 10-Gb/s RZ optical communication system

We report an experiment of adaptive compensation for first-order polarization mode dispersion (PMD) in 10-Gb/s return zero (RZ) optical communication system. The compensated differential group delay (DGD) is up to 30 ps. The quasi-real-time, less than one second, PMD compensation is realized. In the experiment, for the first time, the algorithm so-called particle swarm optimization (PSO) is used to control feedback compensation system.     

An experiment of automatic PMD compensation in 40-Gb/s RZ optical communication system

An experiment of adaptive polarization mode dispersion (PMD) compensation for 40-Gb/s return-to-zero (RZ) optical communication system is reported. In the experiment, degree of polarization (DOP) is used as feedback signal and particle swarm optimization (PSO) method is adopted as logic control algorithm.The compensation time is about 200 ms, the compensated differential group delay (DGD) is up to 30 ps,and bit error rate (BER) of 10-9 is reached when PMD compensation is employed.     

PMD compensation using a fuzzy automatic polarization controller

A new first-order polarization mode dispersion (PMD) compensation technique is experimentally demonstrated in a 2.5 Gbit/s optical transmission system. It achieves adaptive compensation over a wide range of differential group delay (DGD) values, since it does not try to compensate it, but to eliminate one of the principal states of polarization by means of a liquid crystal polarization controller and a polarizer. The PMD parameters of the received signal are measured in real time through its spectrum analysis, and used as the feedback signal in a fuzzy logic algorithm controlling the liquid crystal device. The algorithm achieves a response time faster than the PMD variations in real links, also featuring endless operation. Moreover, a deterministic compact PMD emulator has been implemented in order to test the PMD compensator system.     

偏振模色散自适应补偿系统对调制码型的适应性分析

偏振模色散(PMD)的自适应补偿已经得到了比较深入的研究。在实验中采用偏振度作为取样反馈信号, 粒子群优化算法(PSO)作为反馈控制算法, 比较了偏振模色散自适应补偿系统对于不同码型的补偿效果。结果表明, 传输信号质量严重恶化的情况下, 补偿之后, 对于不同的传输码型, 接收信号的误码率都可以达到一般光纤通信系统的基本要求(10-9), 说明了PMD自适应补偿系统对于各种调制码型都具有良好的补偿效果, 还可以看出, NRZ码相对于其他码型有较高的功率代价, 而RZ50码型在补偿系统中的接收性能最佳。