A Theory of Nonlinear Signal-Noise Interactions in Wavelength Division Multiplexed Coherent Systems

TL;DR

This paper develops a comprehensive, efficient theory for nonlinear signal-noise interactions in wavelength division multiplexed fiber-optic systems, accounting for various physical effects and enabling better system performance estimation.

Contribution

It introduces an exact, first-order perturbation-based theory that includes all cross-channel nonlinearities and is significantly faster than previous models.

Findings

The theory accurately models nonlinear distortions in complex fiber systems.

It shows the impact of signal-noise interactions on system performance.

The approach is computationally efficient for practical system design.

Abstract

A general theory of nonlinear signal-noise interactions for wavelength division multiplexed fiber-optic coherent transmission systems is presented. This theory is based on the regular perturbation treatment of the nonlinear Schrodinger equation, which governs the wave propagation in the optical fiber, and is exact up to the first order in the fiber nonlinear coefficient. It takes into account all cross-channel nonlinear four-wave mixing contributions to the total variance of nonlinear distortions, dependency on modulation format, erbium-doped fiber and and backward Raman amplification schemes, heterogeneous spans, and chromatic dispersion to all orders; moreover, it is computationally efficient, being 2-3 orders of magnitude faster than the available alternative treatments in the literature. This theory is used to estimate the impact of signal-noise interaction on uncompensated, as well as on nonlinearity-compensated systems with ideal multi-channel digital-backpropagation.