Adaptive electronic equalization for non-ideal optical coherent receivers

Abstract

In coherent optical systems, apart from fiber chromatic dispersion and polarization mode dispersion, transmitter and local oscillator phase noise and intermediate frequency offset also have a significant impact on the systempsilas performance. We study, by simulation, the performance of adaptive equalization, assisted by a recursive phase noise-removing unit, on the combined impact of the above effects. An intermediate frequency offset larger than 300 MHz induces an SNR penalty over 6 dB, whereas the systempsilas tolerance over phase noise is larger, allowing for the use of lasers with linewidth equal to almost 30 MHz, with less than 4 dB penalty.