High power, broadly tunable all-solid-state synchronously-pumped lithium triborate optical parametric oscillator

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 μm 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 ~700 W.