A Generalized Raman Scattering Model for Real-Time SNR Estimation of Multi-Band Systems

We investigate the impact of stimulated Raman scattering (SRS) in multi-band transmissions. We first derive and test against numerical results an extended Christodoulides-Zirngibl (ECZ) SRS model based on a triangular approximation of the Raman gain. Then, we exploit the ECZ SRS model in the context of the Gaussian noise (GN) model. We generalize some known closed-form expressions of the self- and cross-phase modulation variances, as well as the amplified spontaneous emission noise variance, over multi-band systems of bandwidth wider than the SRS bandwidth, i.e., beyond the C+L band. Finally, the proposed theoretical model is used to estimate the performance of multi-band systems in terms of signal-to-noise ratio (SNR) and achievable information rate (AIR).