The performance of a high-power all-solid-state synchronously pumped optical parametric oscillator based on a Brewster-angled lithium triborate crystal is reported. The pump scheme includes a diode-pumped amplifier stage to boost the mean output power from an additive-pulse mode-locked Nd:YLF laser by a factor of 2. Improvements in the efficiency for an external resonant frequency doubler have produced a useful output power of 660 mW at 523.5 nm for pumping the optical parametric oscillator. Temperature-tuned noncritical phase matching of the lithium triborate crystal permitted generation of continuously tunable radiation over the range 0.65-2.7 mu m with mean output powers for the signal (idler) as high as 210 mW (110 mW) in the standard X-fold resonator. The high intracavity power of the resonated signal wave introduced nonlinear chirping of the emitted pulses. With prisms to provide intracavity dispersion compensation, nearly transform-limited pulses of 1.63-ps duration were generated with mean output power of as much as 140 mW, i.e., peak powers of similar to 700 W. (C) 1995 Optical Society of America