Pulse characteristics of an optical parametric oscillator pumped by sub-30-fs light pulses

We obtained nearly transform-limited light pulses of 34 fs near 1.2 mu m by pumping an optical parametric oscillator with a a-mm-long KTP crystal by 2 6-fs pulses from a Ti:sapphire laser. The average power of the pulses that were obtained was greater than 50 mW, at an 80-MHz repetition rate. Attempt s to downscale the pulse duration by decreasing the pump-pulse duration rev ealed remarkable limitations of the attainable pulse length for sab-30-fs p ump pulses, in accordance with a recent theoretical study [J. Opt. Sec. Am. B 17, 741 (2000)]. (C) 2000 Optical Society of America. OCIS codes: 320.71 10, 320.2250, 140.7090, 190.4970.