Methods of Step-Size Distribution Optimization Used in S-SSFM Simulations of WDM Systems

Brief review of methods used for simulation of signal propagation in wavelength division multiplexed (WDM)links is presented. We propose two novel methods of stepsize distribution optimization used to improve symmetrized split step Fourier method (S-SSFM) numerical efficiency: presimulated local error S-SSFM (PsLE S-SSFM) and modified logarithmic (ML S-SSFM). The PsLE S-SSFM contains two stages: in the initial stage step-size distribution optimization is carried out by combining local error method and presimulation with signal spectrum averaging; in the second stage conventional SSFM is used by applying optimal step-size distribution obtained in the initial stage. The ML S-SSFMis generalization of logarithmic method proposed to suppress spurious FWM tones, in which a slope of logarithmic step-size distribution is optimized. Overall time savings exceed 50%, depending of a simulated system scenario.