Automatic polarization-mode dispersion compensation by a particle-swarm optimization method and adaptive dithering algorithm

Abstract

We demonstrate multistage polarization-mode dispersion (PMD) compensation numerically and experimentally by using a particle-swarm optimization (PSO) algorithm in the searching process and an adaptive dithering algorithm in the tracking process. PMD compensation in a 40-Gb/s nonreturn-to-zero (NRZ) system based on the algorithm with a global neighborhood structure in one channel and in two channels is explored numerically. The numerical results show that the PSO algorithm is very efficient for multiple-degree-of-freedom PMD compensation systems. For high-PMD compensation the algorithm with a local neighborhood structure is more efficient than that with a global neighborhood structure. We also investigate the performance of PSO in an experiment, where 4-degree-of-freedom PMD compensation is demonstrated in 10-Gb/s NRZ and return-to-zero (RZ) systems. The total search time with the PSO algorithm is several hundred milliseconds, and the response time for the compensator to recover from a sudden disturbance is less than 20 ms.