Polarization Compensation in a WDM/PolSK Fiber Communication System with a Dynamic Polarization Compensator

We successfully built up a dynamic polarization compensator with a feedback control circuit. The compensator can compensate the variation of ellipticity less than 3 °, and the best performance of the DOP is 78.94%.

I. Introduction

Because of the higher bit rate in the fiber communication system, the application of multilevel encoding technique should be developed. The polarization shift keying (PolSK) is one of the attractive modulation schemes which can extend communication capacity but without occupying more bandwidth [1]. PolSK transmission encodes information on a constellation of signal point in the space of the Stokes parameters. Although PolSK is a well multilevel encoding technique, there is an inherent problem with PolSK that the conventional fiber-optic communication channel causes a random and time varying change of the state of polarization (SOP) of the carrier lightwave [2]. Therefore, how to compensate the polarization fluctuation and then stabilize the SOP becomes an important issue in PolSK fiber-optic communication system.