Critical Issues in the Modeling of WDM Systems in the Linear and Nonlinear Regimes

Critical aspects of wavelength division multiplexing (WDM) system in linear and nonlinear regimes were analyzed. A recirculating loop experiment was performed using fourteen 10 Gb/s NRZ-modulated channels with a channel spacing of 50 GHz. Q-factors were calculated for each channel after five circulations through the loop using three different input power levels. It was found that while scalar simulations were adequate in the linear and mildly nonlinear regimes, both states of polarization must be accounted when nonlinear impairments dominate due to the strong interaction between polarization mode dispersion and cross-channel nonlinearities.