Performance analyses of polarization demultiplexing based on constant-modulus algorithm in digital coherent optical receivers

In the digital coherent optical receiver, we can achieve polarization demultiplexing in the digital domain, using a two-by-two matrix controlled by the constant-modulus algorithm (CMA). In this paper, after elucidating the physics behind CMA for polarization demultiplexing, we discuss the performance limit of CMA-based polarization demultiplexing through computer simulations. The method of improving its performance is also demonstrated.