可补偿二阶偏振模色散的两级自适应补偿器研究

研制了对于10Gbit／s非归零码(NRZ)和归零码(RZ)光纤通信系统的二阶偏振模色散(PMD)自适应补偿实验系统。实验中运用光纤链路中的偏振度(DOP)作为反馈控制信号，采用粒子群优化算法(PSO)作为偏振模色散自适应补偿的搜索和跟踪控制算法，粒子群优化作为补偿搜索算法具有收敛速度快、抗噪声和避免陷入局部极值的优点；作为跟踪算法可以快速跟踪偏振模色散的随机变化。实验证明，该补偿系统可以同时补偿一阶和二阶偏振模色散。不论对于非归零码还是归零码，补偿后眼图恢复很好。补偿搜索时间为几百毫秒。跟踪系统对于链路中突发的偏振模色散变化的响应恢复时间小于20ms，实现了准实时的一阶和二阶偏振模色散自适应补偿与跟踪。

Experiment of Adaptive Polarization Mode Dispersion Compensation up to Second Order with a Two-Stage Compensator

An adaptive polarization mode dispersion (PMD) compensation experiment for 10 Gbit/s nonreturn to zero (NRZ) and return to zero (RZ) optical fiber communication systems with a two stage compensator is successfully realized, in which degree of polarization (DOP) feedback signal is used as PMD monitor. The algorithm so called particle swarm optimization (PSO) is used in optimum searching and tracking process. It was proved that in the optimum searching process, the PSO algorithm has the characteristics of rapid convergence to the global optimum rather than being trapped in local sub optima and robust to noise. In the tracking process, the algorithm can track the random changed PMD with fast speed. The compensator shows its ability to compensating the first and second order PMD at same time. After compensation the eye diagrams can be well recovered both for NRZ and RZ formats. The searching process is finished within several hundreds of milliseconds and the response time of recovering to optimum for a sudden PMD disturbance is less than 20 milliseconds. The quasi real time adaptive PMD compensation is realized.