On Numerical Simulations of Ultra-Wideband Long-Haul Optical Communication Systems

This paper discusses the key issues in reliable modeling and numerical simulation of ultra-wideband (UWB) long-haul fiber-optic systems, such as those spanning the C+L band. We analyze the complexity of the split-step Fourier method (SSFM), including modern scenarios based on graphical processing units (GPU), and its numerical setup for accurate simulations. We explain why using the Manakov equation in the nonlinear step of the SSFM remains a good solution also in the UWB scenario, even though the underlying assumptions may be violated. We next propose a technique, called virtual channel grouping, to speed up SSFM simulations in the UWB regime. Importance sampling-based techniques are proposed to speed up the computation of the enhanced Gaussian noise (EGN) model, with computational times of the order of seconds. With such novel solutions, accurate simulations are feasible even for UWB systems.