1 μm-pumped optical parametric generator and oscillator based on orientation-patterned gallium phosphide

We report a pulsed optical parametric generator (OPG) and optical parametric oscillator (OPO) based on the newly developed semiconductor nonlinear crystal, orientation-patterned gallium phosphide (OP-GaP), pumped by a Q-switched Nd:YAG laser at 25 kHz repetition rate. Using a 40-mm-long OP-GaP crystal under temperature tuning, we have generated signal and idler output tunable across 1721-1850 nm and 2504-2787 nm, respectively, with a single grating period of 15.5 μm. For a pump power of 2 W, a total output power of up to 18 mW was obtained. Transmission measurements of pump polarized along [100] axis of the OP-GaP crystal show a drop in transmission with increasing temperature. The OPG threshold increased from 0.6 W at 25 kHz to 4.7 W at 90 kHz. In the singly-resonant OPO operation, a higher idler power of 12.7 mW at 2670 nm was generated for a pump power of 2.2 W. The OPO idler power varied from 9.1 mW at 2530 nm to 7.9 mW at 2752 nm, with a highest power of 10.9 mW obtained at 2626 nm. For a fixed pump pulse energy of 88 μJ, when increasing the repetition rate from 25 kHz to 65 kHz, the OPO idler power at 2670 nm dropped from 12.3 mW to 0.7 mW. The OPG total output power exhibited a passive stability of 0.9% rms with mean values of 18.15 mW whereas the OPO idler exhibited a passive power stability of 1.2% rms with a mean value of 12.68 mW at 2670 nm.