Soliton resonant radiation in phase-matched second-harmonic generation

We investigate both analytically and numerically the optical resonant radiation of bright, dark, and Peregrine solitons in a phase-matched second-harmonic generation process, when they undergo a large temporal walk-off. By virtue of approximate analytical soliton solutions, we obtain simple yet universal formulas for their resonant radiation frequencies, all of which show a good agreement with numerical simulations. We unveil that the optical resonant radiation occurs solely when the second-harmonic component has a normal group-velocity dispersion, and the temporal walk-off tends to stabilize the soliton evolution, by reducing the resonant radiation even in the phase-matched regime. These findings have significantly generalized previous results and will shed more light on the mechanism behind the generation of dispersive waves in quadratic media.