Constant step-size analysis in numerical simulation for correct four-wave-mixing power evaluation in optical fiber transmission systems

Accurate evaluation of four-wave-mixing (FWM) contributions is one of the m ost time consuming problems in numerical simulations of wavelength-division -multiplexed lightwave systems, A too large constant step size can lead to widely overestimate the output FWM power. In this letter, for the first tim e to our knowledge, we analyze the maximum allowed constant step size to be utilized in split-step Fourier method simulations, for obtaining a given a ccuracy in the FWM power evaluation. A very general rule is given, valid fo r any possible value of fiber dispersion, channel separation, channel power and number of channels considered in the simulation.