The Gaussian Noise Model in the Presence of Inter-Channel Stimulated Raman Scattering

A Gaussian noise (GN) model, precisely accounting for an arbitrary frequency dependent signal power profile along the link, is presented. This allows accurate evaluation of the impact of inter-channel stimulated Raman scattering (ISRS) on the optical Kerr nonlinearity. Additionally, the frequency dependent fiber attenuation can be taken into account and transmission systems that use hybrid amplification schemes can be modeled, where distributed Raman amplification is partly applied over the optical spectrum. For the latter two cases, a set of coupled ordinary differential equations must be numerically solved to obtain the signal power profile yielding a semianalytical model. However for lumped amplification and negligible variation in fiber attenuation, a less complex and fully analytical model is presented denoted as the analytical ISRS GN model. The derived model is exact to first-order for Gaussian modulated signals and extensively validated by numerical split-step simulations. A maximum deviation of only 0.1 dB in nonlinear interference power between simulations and the ISRS GN model is reported. The model is applied to a transmission system that occupies the entire C + L band (10 THz optical bandwidth). At optimum launch power, changes of up to 2 dB in nonlinear interference power due to ISRS are reported. The ISRS GN model is quantitatively compared with other models published in the literature and found to be significantly more accurate.