New Branch Metrics for MLSE Receivers Based on Polarization Diversity for PMD Mitigation

In this paper, we analyze the performance of polarization-diversity receivers employing maximum-likelihood sequence estimation (MLSE) to combat the effects of polarization mode dispersion (PMD) for both the intensity-modulation direct detection (IMDD) and duobinary modulation formats at 43 Gb/s. We propose and study several parametric branch metrics, showing that the use of MLSE receivers based on polarization diversity with appropriate branch metrics allows to cancel out the high penalty incurred by standard MLSE receivers in the presence of PMD.