Radiation resistance of nonlinear crystals at a wavelength of 9.55 μm

The results of radiation resistance measurements for twelve nonlinear crystals are presented. The crystals include the well-known nonlinear CdGeAs₂, ZnGeP₂, AgGaSe₂, GaSe, AgGaS₂, and Ag₃AsS₃ crystals operating in the middle IR range, new mixed AgGaGeS₄ and Cd_0.35Hg_0.65Ga₂S₄ crystals, two-phase (orange and yellow) HgGa₂S₄ crystal, and the doped GaSe:In crystal. The mixed crystals and the two-phase HgGa₂S₄ crystal are transparent in the range from 0.4 — 0.5 to 11.5 — 14.5 μm. The measurements were performed using a pulsed single-mode highly stability TEA CO₂ laser with an output pulse duration of ~30 ns. The damage thresholds of new nonlinear AgGaGeS₄ and Cd _0.35Hg_0.65Ga₂S₄ crystals and of the HgGa₂S₄ crystal (the orange and yellow phases) were found to be 1.5 — 2.2 times higher than for the crystals operating in the middle IR range.