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P_S和消偏的背景噪声P_N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。

An adaptive PMD compensation method used in WDM system is proposed,in which a polarization scrambler is combined with principal orthogonal polarization splitting detection to realize multi-channel DOP detection. Optical signal-noise ratio (OSNR) is obtained from the measurement of P_S and P_N,and according to the relationship of OSNR and DOP,the monitoring of DOP can be implemented. The searching and tracking of DOP is achieved by particle swarm optimum (PSO) algorithm. After the D/A conversion,the voltages ranging from 0 to 10 V are performed on the polarization controller to adjust the principle polarization state of signal. Thus,a close-loop feedback control module can be built up ,and through several iteration,the optimum of DOP is obtained and the adaptive PMD compensation is achieved. After compensation,the eye opening is improved obviously,which demonstrates the effectiveness of the compensation method.