A novel compensation method of transmitter IQ mismatch considering laser phase noise for CO-OFDM

In this paper, a novel compensation method for transmitter (Tx) in-phase/quadrature (IQ) mismatch is proposed in coherent optical orthogonal frequency division multiplexing (CO-OFDM) system considering laser phase noise. A new mathematical model is deduced, based on the given model, laser phase noise and channel distortion are combined as a new channel transfer factor, and both distortions can be eliminated in the equalization process, then the IQ mismatch distortion is compensated by using the equalized symbol. Simulation results show that when the phase and amplitude mismatch are 15° and 3 dB respectively, a 2.4 dB optical signal-to signal ratio is improved for 60 kHz of the laser line-width, and the tolerable laser linewidth can be improved by 98 kHz. Furthermore, the complexity of the proposed method is reduced by 43% compared with the DA in terms of the number of required complex multiplications per bit.