Tunable femtosecond-pulse generation by an optical parametric oscillator in the saturation regime

We demonstrate the generation of powerful, bandwidth-limited pulses in a KTP optical parametric oscillator synchronously excited by the pulse train of a f lash-lamp-pumped, mode-locked Nd:YLF laser. Operating the optical parametric oscillator a factor of 4 above threshold and optimizing the cavity length yields pulses of 260 +/- 30 fs. The shortening by a factor of 15 relative to the pump is accompanied by extended pulse wings. Tunability of the device is shown in the wavelength range 1.2 -1.6 microm.