Soliton propagation and frequency down-conversion in the medium with combined nonlinear response

In this report, we study theoretically and numerically the soliton propagation of laser radiation in the medium with quadratic and cubic nonlinear response. We show that, for high-intensity femtosecond pulses with a large phase mismatch of the interacting waves, soliton propagation of two-color laser radiation with similar peak intensities of interacting waves is possible. Our investigation is based on two coupled nonlinear Schrödinger equations. Using a multiscale approach, we derive an approximate analytical solution for two-color laser radiation propagation in the soliton mode. Based on numerical simulation, high-efficient frequency down conversion is demonstrated when switching the two-color soliton mode to the soliton mode with high peak intensity at the fundamental frequency.