Comparative Analysis of Optical Damage in Advanced Barium Chalcogenides Nonlinear Crystals at 1-μm and 2-μm

Widely tunable optical parametric oscillators (OPOs) are attractive sources for applications in mid-IR due to the scarcity of direct-emitting conventional lasers in this spectral region. Recently, two new chalcogenide compounds BaGa
4
Se
7
(BGSe) and BaGaGe
2
Se
6
(BGGSe) having relatively high χ
⁽²⁾
nonlinear optical coefficient were successfully synthesized and large single crystals were grown using the Bridgman-Stockbarger technique [1, 2]. Recently the first BGSe nanosecond OPO pumped by a Q-switched Nd:YAG laser (1.064 μm) [3] and pumped at 2.09 μm by a Q-switched Ho:YAG laser [4] were demonstrated. Lastly, an intracavity pumped cascaded OPO based on BGGSe was reported [5]. The continuous development and power-scaling of BGSe and BGGSe — based OPOs require study of their damage thresholds. This paper is devoted to a comparative analysis of optical damage of the BGSe and BGGSe nonlinear elements pumped by 1-μm or 2-μm laser radiations.