A high-repetition-rate Ti:sapphire laser is used to synchronously pump a type-II angle-tuned CsTiOAsO4 (CTA) optical parametric oscillator. When pumped at 809 nm, the optical parametric oscillator is tunable from 1.007 to 1.180 mu m in the signal branch and hom 2.590 to 4.120 mu m in the idler branch. Powers as high as 235 mW are obtained in the signal branch. Pulse widths as short as 56 fs are generated at 1.115 mu m. CTA is shown to have a unique combination of low walk-off and low dispersion that contributes to its high gain and conversion efficiency. (C) 1995 Optical Society of America