Adaptive Polarization Control for Coherent Optical Links with Polarization Multiplexed Carrier

Self-homodyne systems with polarization multiplexed carrier offer an local oscillator-less (LO-less) coherent receiver with simplified signal processing requirement that can be a good candidate for high-speed short-reach data center interconnects. The practical implementation of these systems is limited by the requirement of polarization control at the receiver end for separating the carrier and the modulated signal. In this paper, effect of polarization impairments in polarization diversity based systems is studied and modeled. A novel and practical adaptive polarization control technique based on optical power feedback from one polarization is proposed for polarization multiplexed carrier based systems and verified through simulation results. The application of the proposed concept is also experimentally demonstrated for a quadrature phase shift keying (QPSK) system with polarization multiplexed carrier.