Performance Evaluation of Phase Estimation Algorithms in Equalized Coherent Optical Systems

We assess the performance of a coherent optical system employing a phase estimation algorithm combined with a least mean square decision-directed equalizer in a feedback configuration and compare it to the constant modulus algorithm with an independent carrier phase estimation approach for 16-quadratic-amplitude-modulation transmission. Both series and parallel implementations are discussed. Hardware issues regarding a recursive implementation of the estimation filter are also reported.