Numerical simulation of continuum generation in a multimode nonlinear waveguide

Continuum generation in large multimode nonlinear waveguides offers the exciting prospect of a new generation of compact, integrated, and high-power broadband light sources. Recently a novel technique based on scanning near-field optical microscopy (SNOM) has been adopted for the observation of continuum generation in such systems with subwavelength resolution.This revealed several interesting aspects of continuum generation, e.g., that the spectral broadening induced by optical nonlinearity depends not only on the distance of propagation but also on the location across the waveguide. Moreover the spectral broadening along the waveguide is slower than in the case of a single-mode waveguide and the spectral width may even decrease over short distances. We have now developed a multimode numerical simulation for nonlinear pulse propagation in order to explain such features.