Optical and generation characteristics of new nonlinear Ba₂Ga₈GeS₁₆ and Ba₂Ga₈(GeSe₂)S₁₄ crystals for the mid-IR range

Ba2Ga8GeS16 and Ba2Ga8(GeSe2)S-14 single crystals of large size and good optical quality have been grown for the first time. Their linear optical characteristics-transmission spectra in the range of 0.3-25 mu m, dispersion of principal refractive indices, and birefringence-have been measured. Irradiation of the crystals by 100-fs laser pulses with a wavelength of 8.3 mu m initiated second-harmonic generation with an efficiency comparable with that obtained for the AgGaS2 crystal.