Numerical calculation for a nanosecond beta-barium borate optical parametric oscillator in a collinear phase-matched geometry

We report a numerical model for a beta-BaB2O4 optical parametric oscillator (OPO) appropriate for nanosecond operation. The Runge-Kutta method with a Fourier-space transform was used to numerically solve the coupled different ial equations describing the interaction among the pump, the signal, and th e idler waves. The temporal profiles and the spatial variations of the pump , the signal, and the idler waves as they propagate through the nonlinear c rystal are presented. The effects of the walkoff are studied by comparing t he conversion efficiencies with and without the walkoff considered.