Linear and nonlinear optical properties of LiInS2

LiInS2 is an AIBIIIC2VI ternary semiconductor crystallizing with mm2 symmetry. The useful transparency range is 0.5–8 μ, over which we have measured the refractive indices. The optical nonlinear coefficients for second harmonic generation have also been measured. The nonlinear figure of merit is comparable to that of AgGaS2. Three‐frequency collinear phase matching is possible in LiInS2 and is analyzed in some detail. LiInS2 is judged to be a potentially more useful optical nonlinear material than the analogous compound LiGaO2.