Modeling nonlinearity in coherent transmissions with dominant intrachannel-four-wave-mixing

Abstract

By extending a well-established time-domain perturbation approach to dual-polarization propagation, we provide an analytical framework to predict the nonlinear interference (NLI) variance, i.e., the variance induced by nonlinearity on the sampled field, and the nonlinear threshold (NLT) in coherent transmissions with dominant intrachannel-four-wave-mixing (IFWM). Such a framework applies to non dispersion managed (NDM) very long-haul coherent optical systems at nowadays typical baudrates of tens of Gigabaud, as well as to dispersion-managed (DM) systems at even higher baudrates, whenever IFWM is not removed by nonlinear equalization and is thus the dominant nonlinearity. The NLI variance formula has two fitting parameters which can be calibrated from simulations. From the NLI variance formula, analytical expressions of the NLT for both DM and NDM systems are derived and checked against recent NLT Monte-Carlo simulations.

An Alternative Approach to the Gaussian Noise Model and its System Implications

“…The first one evaluates the integral in closed-form over the distance, leaving a double integral over the frequency domain [6], [23], [28] …”

“…Several analytical models for performance evaluation and design of such systems have been proposed [6]- [10], which all share the same underlying basic assumption that nonlinearity is a small perturbation of the nonlinear Schrödinger equation (NLSE) of propagation. Among these, the GN model developed in [8], [10] is particularly attractive since it is able to provide a Manuscript received July 11, 2013; revised September 24, 2013; accepted September 28, 2013.…”

“…In [14] we proposed an alternative proof working in the frequency domain. All these proofs start from the main integral equation describing the RP NLI field [6], [15] as a sum of cubic beating terms weighted by the kernel of the integral equation.…”

Accumulation of nonlinear noise in coherent communication lines without dispersion compensation

“…This nonlinear noise can be described as a Gaussian noise [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], at least in dispersion uncompensated (DU) coherent systems. Gaussian nature of the nonlinear interference (NLI) noise fields is conditioned by Gaussian distribution of the information sampled signal [4][5][6][14][15][16].…”

GN-Model Validation Over Seven Fiber Types in Uncompensated PM-16QAM Nyquist-WDM Links

“…In the UT scenario, it has been shown that one possible way of modeling the effect of fiber nonlinearity is to approximate its impact as an additive Gaussian disturbance [1][2], called nonlinear interference (NLI). Several non-linear propagation models are available that allow to estimate the power of the NLI produced in a given link, among which [3][4][5][6][7][8][9]. In particular, [3][4], [6], [8][9] provide rather similar results.…”