Efficient mid-infrared laser using 19-µm-pumped Ho:YAG and ZnGeP_2 optical parametric oscillators

Abstract

We report >4.2-W mid-infrared (mid-IR) output (3.8 and 4.65 µm) and >2.1 W at 3.5 µm in ZnGeP2 (ZGP) optical parametric oscillators (OPO) pumped by a holmium-doped yttrium aluminum garnet (Ho:YAG) laser, directly pumped by a diode-pumped 1.9-µm thulium-doped yttrium lithium fluoride (Tm:YLF) laser. Optical-to-optical efficiency achieved is >7.2% (laser diode to mid-IR). In addition, a Ho:YAG-pumped ZGP OPO operation is achieved over a Ho:YAG temperature range of 80 °C at the 8-W (Ho:YAG) and 3-W (ZGP OPO) power levels.