Mid-IR absorption in AgGaSe₂ optical parametric oscillator crystals

We report new experimental results on the spectral, thermal, and orientational characteristics of stoichiometry-dependent mid-IR absorption in AgGaSe(2) crystals. In currently available material, this absorption poses an obstacle to the power scaling of the 2-µm-pumped AgGaSe(2) optical parametric oscillator (OPO). Preliminary experiments have indicated that this absorption could be substantially reduced by optimization of the process parameters during crystal growth and annealing. OPO output powers approaching 10 W may be achievable by using optimized material.