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

Abstract

The performance of a high-power all-solid-state synchronously-pumped optical parametric oscillator (OPO) based on a Brewster-angled lithium triborate (LBO) 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 two. Improvements in the efficiency of an external resonant frequency-doubler have produced a useful output power of 660mW at 523.5µm for pumping the OPO. Temperature-tuned noncritical phase matching of the LBO crystal allowed generation of continuously tunable radiation over the range 0.65-2.7µm with mean output powers for the signal (idler) as high as 210mW (110mW) 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 1.63psec duration were generated with mean output power up to 140mW, ie. peak powers of ~700W