Mitigation of Rayleigh backscattering in 10-Gb/s downstream and 2.5-Gb/s upstream DWDM 100-km long-reach PONs

Abstract

Long-reach passive optical network (LR-PON) is considered as a promising technology towards higher capacity and extended coverage optical system. We propose and demonstrate a LR-PON with the capability of Rayleigh backscattering (RB) noise mitigation. By using the upstream signal wavelength-transition generated by a dual-parallel Mach-Zehnder modulator (DP-MZM) based colorless optical networking unit (ONU), the spectral overlap among the upstream signal and the RB noises can be minimized. Hence, due to the achievement of effective RB mitigation, a 100 km LR-PON with a high split-ratio of 512 is demonstrated using 10 Gb/s non-return-to-zero (NRZ) downstream and 2.5 Gb/s NRZ upstream signals. Detail analysis of the wavelength-transition generation is presented. (C) 2011 Optical Society of America