Iterative phase noise estimation and suppression for CO-OFDM systems with large laser linewidth

In order to further improve the laser phase noise tolerance of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems, an iterative phase noise suppression algorithm is proposed in this paper, which is powerful in mitigating the laser phase noise induced intercarrier interference (ICI) even when laser linewidth achieves 2 MHz. Compared with the existing ICI suppression method, the performance gain brought by the proposal is significant when the laser linewidth is larger than 1.5 MHz. The BER floor which can not be avoided by using the existing phase noise suppression methods can be reduced effectively by employing the new iterative algorithm.