Conjugate nonlinear-optical loop mirror (Conj-NOLM)-based phase-preserving multilevel amplitude regenerator

Abstract

We propose a novel phase-preserving multilevel amplitude regenerator scheme by cascading two nonlinear-optical loop mirrors (NOLMs) with an intermediate optical phase conjugator (OPC) stage. Joint parameter optimization of the two NOLM units has been carried out to cancel the introduced phase distortion and enable a more power-efficient performance. Moreover, our scheme combines the operation of the NOLM and the OPC in a single subsystem, enabling the compensation of both amplitude and phase distortions when located symmetrically in a transmission link. To this end, extensive numerical simulations have been performed to evaluate the regeneration performance in a transmission link dominated by amplified spontaneous emission (ASE) noise and Kerr-induced nonlinear distortions (self-phase modulation-induced phase distortion), achieving over 100% reach extension compared to the cases of un-regenerative, or a mid-span OPC-based transmission links.