Narrowband mid-infrared optical parametric generator based on a type-II BaGa4Se7 crystal

In this Letter, we first reported on a mid-infrared double- pass optical parametric generator (OPG) based on a single type-II phase-matching BaGa4Se7 4 Se 7 (BGSe) crystal, pumped at 2.1 mu m. The OPG achieved a maximum pulse energy of 55 mu J for generating narrowband mid-infrared laser pulses. The signal and idler lights exhibited center wavelengths of 4.04 and 4.33 mu m, respectively, with bandwidths of 18.6 nm (11.4 cm-1) - 1 ) and 20.4 nm (10.9 cm-1). - 1 ). To improve the output performance, we utilized a cascaded scheme of type-I ZnGeP2 2 (ZGP) and type-II BGSe crystals. The spectral bandwidths of the signal and idler lights, nearing 4 mu m, were narrower than 170 nm (90 cm-1), - 1 ), representing a significant improvement over the ZGP OPG. The cascaded OPG achieved a remarkable total optical-to-optical conversion efficiency (OOCE) of 14.9% and a maximum pulse energy of 0.329 mJ. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.