Optimization of Two-Stage Higher-Order PMD Compensator with Five Degrees of Freedom

In this paper, the optimal length of the fixed delay line (FDL) for a two-stage polarization mode dispersion (PMD) compensator with five degrees of freedom (DOF) is investigated, for the first time, for a 40 Gbit/s NRZ optical fiber transmission system by implementing genetic algorithm in the logic-control unit. It is found that there exists an optimal length of FDL for such an optical higher-order PMD compensator (PMDC) with five DOFs, and the optimal length of the FDL is about 1.2 times the PMD value of the preceding transmission fiber to be compensated for. Such an optimized two-stage PMDC can achieve a close performance to that of a double stage PMDC with six DOFs of two variable delay lines.