A DSP-Based Monitor Algorithm for Time-Varying Trajectory and Rotation Speed of Principal States of Polarization

We propose a DSP-based algorithm for monitoring PSP trajectories and rotation speeds. By using sliding-window median-filtering and modulus judgment method, the algorithm can precisely recover the PSP trajectories and determine the rotation speeds more accurately.

I. Introduction

In polarization division multiplexing (PDM) coherent optical communication systems, the polarization mode dispersion (PMD) is one of the most important signal impairments in the channel. PMD introduces differential group delay (DGD) between the two orthogonal principal states of polarization (PSP), and an optical pulse containing both PSPs will be broadened or even split after transmission, resulting in misjudgment of the signal code stream by the optical receiver and thus higher bit-error rates. Therefore, PMD compensation to eliminate the damage on the signal is essential in high-speed PDM optical communication systems.