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40 Gb/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1560.5 nm处, 差分群时延补偿前后测量值分别为21 ps和1.3 ps,而二阶偏振模色散补偿前后测量值分别为266 ps2和43.5 ps2。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1 dB。

Polarization mode dispersion (PMD) has been the major limiting factor for long-haul high-speed optical fiber transmission and the PMD adaptive compensation is required urgently. An experiment of two-stage adaptive compensation for polarization mode dispersion in a 40 Gb/s RZ optical time-division multiplexed (OTDM) communication system is reported. The particle swarm optimization (PSO) algorithm with the six degrees of freedom (DOF) is adopted to maximize the degree of polarization (DOP) and realizes the adaptive PMD compensation. The compensation process is completed within several hundred milliseconds. The method of Poincaré sphere (PS) is applied to measure the PMD values in the experimental fiber link. The results show that the DGD decreases from 21 ps to 1.3 ps and the second PMD descends from 266 ps2 to 43.5 ps2 in central wavelength of 1560.5 nm. The first and second order PMD are compensated together in different degree and the whole system power penalty is less than 1 dB (@BER 10-9) after PMD adaptive compensation.