Pilot-Based Phase Noise, IQ Mismatch, and Channel Distortion Estimation for PDM CO-OFDM System

In this letter, a pilot-based method is proposed to suppress three non-ideal factors, including channel distortion, transmitter in-phase and quadrature (IQ) mismatch, and laser phase noise for polarization division multiplexed coherent optical orthogonal frequency division multiplexing systems. Compared with the conventional phase noise and IQ mismatch estimation methods which only consider one of the two non-ideal factors, we deduce a novel mathematical model considering both and compensate them with special designed pilots: the channel distortion and IQ mismatch are compensate by the block-type pilot while the comb-type pilot is used to estimate phase noise. The simulation results proved that our method can not only better compensate the non-idealities factors, but also can provide high speed transmission with 120 Gb/s over 400-km transmission compared with the conventional methods.