Singly-resonant pulsed optical parametric oscillator based on orientation-patterned gallium phosphide

We report a pulsed singly-resonant optical parametric oscillator (OPO) based on the new nonlinear crystal, orientation-patterned gallium phosphide (OP-GaP). Pumped by a Q-switched Nd:YAG laser at 1064 nm, and using a 40-mm-long OP-GaP crystal with a single grating period of Λ=16 μm, the OPO generates signal and idler output across 1.6-1.7 μm and 2.8-3.1 μm, respectively, under temperature tuning. For an average pump power of 4.8 W at 50 kHz pulse repetition rate, mid-infrared idler powers of up to ∼20 mW have been obtained at 2966 nm with high output stability. For pump pulses of ∼13 ns duration, the OPO generates ∼6 ns output signal pulses. From temperature-dependent wavelength tuning measurements at two different pump powers of 4.2 W and 1.2 W, a discrepancy of 11-17°C in the internal crystal temperature is estimated, implying that the OP-GaP sample suffers from increasing thermal effects at higher pump powers due to absorption.