Numerical study on combined stimulated Raman scattering and self-phase modulation in optical fibers influenced by walk-off between pump and Stokes pulses

Abstract

We numerically examine the dynamics of stimulated Raman scattering combined with self-phase modulation for intense 100-psec-long input pulses in a dispersive single-mode optical fiber. Linear dispersion is treated in a first-order approximation by introducing group-velocity mismatch between pump and Stokes pulses. It is shown how this mismatch combined with pump depletion leads to asymmetric distortions of both pulse shapes and frequency chirps. The resulting delay of the Stokes peak is found to reach higher values for lower input pump powers. For sufficiently long fibers the emerging pump pulse has a one-peak structure, in contrast to the two-peak structure in the dispersionless case. The existence of an optimum fiber length to obtain the shortest Stokes pulse for a given input pulse is shown.