Femtosecond self-doubling optical parametric oscillator based on KTiOAsO/sub 4/

We report a femtosecond intracavity-frequency-doubled optical parametric oscillator that employs a single KTiOAsO4crystal for both parametric generation and frequency doubling. This device generates a yellow output beam at 575 nm with 39.4% power conversion efficiency when synchronously pumped by a femtosecond Ti:sapphire laser at a wavelength of 796 nm. An intracavity retarder is employed to alleviate temporal pulse overlap problems associated with group velocity mismatch inside the KTiOAsO4crystal.