Compact, efficient 344-MHz repetition-rate femtosecond optical parametric oscillator

We describe configurations of a novel synchronously pumped femtosecond optical parametric oscillator based on the crystal RbTiOAsO(4) and operating with a signal-pulse-repetition frequency as high as 344 MHz. Average signal powers as high as 600 mW and pulse durations of 78 fs are demonstrated at a wavelength of 1.25 microm, and a characterization of the signal output using frequency-resolved optical gating implies asymmetric near-sech(2)(t) intensity-profile pulses with significant amounts of spectral cubic phase.