Widely Tunable BaGa2GeSe6 Optical Parametric Amplifier Pumped by a Mode-Locked Nd: YAG Laser

Powerful and compact coherent mid-infrared radiation source is crucial for a vast number of applications. A widely tunable 3- $15~\mu $ m optical parametric amplifier with BaGa2GeSe6 crystal pumped by a picosecond mode-locked 1064 nm laser was demonstrated for the first time. Type-I produced a maximum energy of $377~\mu $ J at $5.2~\mu $ m, while type-II achieved a maximum energy of $294~\mu $ J at $6.7~\mu $ m under the incident pump energy of 11.8 mJ, corresponding to the pump-to-idler energy efficiency of 3.2% and 2.5%, respectively. Furthermore, the corresponding phase-matching angles for 3– $15~\mu $ m were measured experimentally. Moreover, the conversion efficiency, typical pulse temporal shapes and beam spatial profiles of idler were calculated based on a BaGa2GeSe6-OPA numerical model. The results indicate the potential of BaGa2GeSe6 pumped at 1064 nm for realizing high-efficiency and high-energy mid-infrared laser radiation.