1.2 W ZnGeP2 optical parametric oscillator

A doubly resonant ZnGeP2 (ZGP) optical parametric oscillator pumped by a Tm,Ho:GdVO4 laser is investigated. High pulse repetition frequency of 10 kHz cryogenic Tm(5%),Ho(0.5%):GdVO4 laser at 2.05 μm was utilized as pumping source for ZnGeP2 OPO. The stable pulse train with duration of 23 ns was achieved from Tm,Ho:GdVO4 laser pumped by a continuous wave fiber-coupled laser diode at 801 nm. The GdVO4 host exhibited good thermo-optical property, experiencing greater than 12 kW/cm2 pump density. The ZGP OPO generated a total combined output of 1.2 W at 3.75 μm and 4.52 μm under pumping power of 5.3 W, corresponding conversion efficiency of 23% from incident 2 μm laser power to mid-IR output.