Performance degradation of 100 Gb/s PM-QPSK and 400 Gb/s PM-16QAM dual carrier coherent systems due to cascaded optical filters

In this paper, we studied the impact of cascading optical filters on a dual-carrier 100 Gb/s and 400 Gb/s systems with 50 and 100 GHz channel spacing; respectively. Eye closure penalty (ECP) is used as a performance evaluation metric, where we use two types of filters: fiber Bragg grating (FBG) and thin-film filters (TFF). Simulation results indicate that at 6-dB ECP, the number of cascaded filters for dual-carrier 100 Gb/s polarization-multiplexed quadrature phase shift keying (PM-QPSK) at 50 GHz channel spacing system is 4 TFF and 2 FBG. In Addition, simulation results indicate that at 6-dB ECP, the number of cascaded filters for dual-carrier 400 Gb/s polarization-multiplexed 16-ary quadrature amplitude modulation (PM-16QAM) system at 100 GHz channel spacing is only a single TFF.