Frequency upconversion by phase-matched sum-frequency generation in an optical parametric oscillator

We report the generation of 0.589-,microm radiation from mixing the pump at 1.064 ,microm and the signal at 1.319 microm of a singly resonant, synchronously pumped AgGaS(2) optical parametric oscillator. A KTP crystal is used for the sum-frequency generation (SFG). Both extracavity and intracavity SFG is demonstrated, with overall conversion efficiencies of 3.5% and 10.5%, respectively. Near-transform-limited pulses of less than 50 ps are generated from 100-ps pulses. With a limited available peak pump power, both spatial orderings of the KTP and the AgGaS(2) crystals for intracavity SFG produce similar conversion efficiency and outputs of similar pulse duration, spectral width, and stability.