High average power LWIR OPA in ZnGeP2 and BaGa4Se7

BaGa4Se7 (BGSe) was utilized as the NLO device for a low repetition rate picosecond OPA of 1.84 um and 2.3 um light to generate 10.2 um LWIR. This was compared to ZnGeP2 (ZGP), which has a higher nonlinear coefficient than BGSe but significant phonon edge absorption at 10.2 um. Experimental results were compared to NLO modelling to understand which material was appropriate for use at 10.2 um, and appropriate sample dimensions for a BGSe OPA. Single and dual stage OPA were explored, and ZGP pumped into BGSe OPA design. Progress on the domestic growth of BGSe crystals further explored.