Optical carrier regeneration based on injection locking for single-sideband self-coherent detection

Abstract

In this work, we demonstrate a low-cost electro-absorption modulated laser (EML)-based coherent receiver enabled by the injection locking technique in a 32-Gb/s single-sideband (SSB) transmission system. We focus on analyzing the harmonic components introduced by injection locking process when injecting an SSB signal into the EML-based coherent receiver and compare them with the harmonic components introduced by the injection-locked laser (ILL)-based coherent receiver. To mitigate the nonlinear impairment caused by the harmonic components, we validate the feasibility of a neural network (NN)-based nonlinear equalizer. We also evaluate the performance of the EML-based coherent receiver in comparison to the ILL-based coherent receiver and the Kramers-Kronig (KK) receiver. The experimental results show that the EML-based coherent receiver can provide a 6.5-dB sensitivity improvement with a 14-dB CSPR reduction compared to the KK receiver after 40 km fiber transmission. If the EAM photodiode has higher responsivity, the proposed reception approach is expected to achieve comparable sensitivity to the ILL-based coherent receiver with lower hardware complexity.