Performance of coherent optical polarization shift keying in the presence of phase noise

The performance of optical coherent modulation schemes using the state of polarization of light as the modulating parameter (POLSK, POLarization Shift Keying) is analyzed, in the presence of laser phase noise. First, we compare three different analysis methods to account for the effects of phase noise in the binary case, and choose the one offering the best trade-off in terms of accuracy/complexity. Successively, we derive a tight upper bound to the performance of multilevel POLSK systems with postdetection filtering. Then, we include phase noise using the best method as tested in the binary case and extensively discuss the performance of binary and various multilevel POLSK constellations, optimized with respect to the IF filter bandwidth. The results show that binary POLSK has a very low sensitivity to phase noise and that multilevel POLSK is even less sensitive than the binary scheme