Enhanced tolerance of rayleigh backscattering in WDM-PONs by using Coded RZ modulation

Rayleigh backscattering (RB) noise is a fundamental limitation for a centralized loopback WDM-PONs based on RSOA in ONU side. By exploring the RSOA chirp induced spectral boarding with DC-balanced line coding, here a novel modulation format called as Coded RZ is proposed to enhance the system tolerance against RB. The results showed that the signal-to-noise (SCR) is improved by about 8 dB and 2.5 dB from the conventional NRZ and RZ modulation formats respectively to maintain the power penalty ≤ 2dB.