Wavelength conversion of high-order QAM signals for future transparent all-optical networks

Abstract

With the recent trend of employing spectrally efficient multi-level modulation formats in optical communication systems, it is highly desirable to exploit the all-optical wavelength conversion (AOWC) schemes for formats, such as 16- or 64-quadrature amplitude modulation (QAM) signals. Since the linear and nonlinear phase noise is transferred with the data to the converted wavelength in AOWC subsystem, it is imperative to optimize the operation condition in AOWC to suppress noise to allow compatibility phase-noise sensitive high-order QAM formats. We first investigate the performance optimization of AOWC for high-order QAMs like 64QAM through four-wave mixing in highly nonlinear fiber, and then discuss our proposed AOWCs schemes for high-order QAM signals such as 16/64-QAM using coherent pumps which is free of phase noise from pumps.