Mid-infrared intra-cavity ZnGeP2 optical parametric oscillator

Abstract

We reported a mid-infrared intra-cavity ZnGeP2 optical parametric oscillator (ZGP OPO) pumped by an acousto-optic (AO) Q-switched Ho:YAG oscillator. The 1908nm laser with an output power of 20W was used as the pump source of the Ho:YAG AO Q-switched oscillator. ZGP OPO was placed inside the Ho:YAG oscillator. Under the Q-switched repetition frequency of 5kHz, the maximum output power of the mid-infrared laser was 1.5W. The optical-optical conversion efficiency of the 1908nm laser to the mid-infrared laser was 7.5%, and the slope efficiency was 15%. The two central wavelengths of mid-infrared laser were located at 3.9~4.05μm and 4.35~4.5μm respectively. The pulse width was 29.9ns and the single-pulse energy was 0.3mJ.