Phase-matched self-doubling optical parametric oscillator

We report a synchronously pumped intracavity frequency-doubled optical parametric oscillator that employs a single KTiOPO(4) crystal for both parametric generation and frequency doubling. Both nonlinear processes are phase matched for the same direction of propagation in the crystal. The parametric oscillator, pumped by a femtosecond Ti:sapphire laser at a wavelength of 745 nm, generates a green output beam at 540 nm with a 29% power conversion efficiency. Angle tuning in conjunction with pump wavelength tuning provides output tunability in the 530-585-nm range.