A Out-of-band Noise Detection and Whitening Method for Polarization Dependent Loss Mitigation

Polarization dependent loss (PDL) has become a major source of linear impairment in the polarization division multiplexing systems. In this paper, an out-of-band noise correlation matrix detection and whitening method is proposed. The out-of-band noise is detected after the signal is filtered at the receiver side and the correlation matrix is obtained afterwards. A noise whitening matrix obtained by singular values decomposition (SVD) is multiplied on the signal with the in-band noise. With the signal transfer matrix estimated by the pilot signals, the maximum likelihood detection method is implemented afterwards. Simulations have been performed to evaluate the performance of the proposed noise whitening method. The Q-factor of the proposed whitening method and the noise whitening method without considering the received noise correlation are compared, and the results show that the proposed PDL mitigation method can be considered as a feasible solution to improve the system performance under PDL.