Computing Large Signal Distortions and Bit-Error-Ratios in DPSK Transmission Systems

We demonstrate the application of importance sampling (IS) to the simulation of a soliton-based differential phase-shift keyed (DPSK) optical transmission system. We use an approximation to the pulse evolution given by perturbation theory and optimized with calculus of variations to guide full numerical Monte-Carlo simulations employing IS. The method not only directly determines the bit error ratio, but also predicts the manner in which large signal distortions occur.