SNR Model for Generalized Droop with Constant Output Power Amplifier Systems and Experimental Measurements

Submarine optical transmission systems are commonly operated with constant output power amplifiers. The Gaussian Noise (GN) model of propagation was generally developed in the context of constant gain amplification and accounts for amplified spontaneous emission (ASE) noise and nonlinear interference (NLI) noise. Recently, new models have been proposed and developed to predict signal-to-noise ratio (SNR) models for systems with constant output power amplification that account for the phenomenon known as signal droop, or more broadly, generalized droop (GD). Here we describe a GD model within the context of noises as generated in the GN model, and then further including other distributed noise generation such as might occur for crosstalk in multicore optical fibers. The model results in simple expressions for SNR, signal power, and noise powers as a function of the number of identical spans. We provide numerical modeling confirmation of the analytical model for different formats, and experimental transmission data that is fully consistent with the model.