High-efficiency 20–50 kHz mid-infrared orientation-patterned GaAs optical parametric oscillator pumped by a 2 μm holmium laser

We report on what are, to our knowledge, the best results obtained with an orientation-patterned GaAs optical parametric oscillator (OPO) pumped by a Q-switched 2 microm Ho:YAG laser. Up to 2.85 W are obtained for 6.1 W of pump power, corresponding to an optical-to-optical conversion efficiency of 46.5% with a threshold of 1 W. Optical damage occurred at a fluence of about 2 J/cm2. The thickness of the crystal limited the pump power. Slope efficiencies are of the same order as those obtained with ZnGeP2 OPOs pumped with the same Ho:YAG laser.