90° phase-matched Hg_(0.35)Gd_(0.65)Ga_2S_4 optical parametric oscillator pumped by a Nd:YAG laser

摘要

This paper reports the 90° phase-matched Hg_(0.35)Gd_(0.65)Ga_2S_4 optical parametric oscillator (OPO) pumped by a Nd:YAG laser at 1.0642 μm in the 8.24-9.40 μm range. The resulting data for the temperature tuning curves of the two idler wavelengths were found to agree well with the theoretical values calculated with the Sellmeier and thermo-optic dispersion formulas constructed from those of HgGa_2S_4 and CdGa_2S_4 presented in our previous paper (K. Kato et al. Opt. Commun. 386, 49-52, (2017)). The OPO threshold was ~ 0.3 W, which is 57% lower than ~ 0.7 W observed for the 8-mm-long HgGa_2S_4 crystal.