INTRODUCTION：

Lithium Thioindate (LiInS2 or LIS) is an A^IB^IIIC₂^VI ternary semiconductor crystallizing with mm2 symmetry.

LiInS2 has a large nonlinear optical (NLO) coefficient, the non-linear characteristics of the crystals are close to AgGaS2 and AgGaSe2, but their crystal structures are different. LiInS2 crustal has a high laser damage threshold, and a wide transparent wavelength range, the useful transparency range of LiInS2 is 0.5–8 μ, which makes it an excellent mid-infrared NLO crystal. LiInS2 is pyroelectric as well, its electro-optical parameters are the base for using it as an effective electro-optical material. Three‐frequency collinear phase matching is possible in LiInS2, LiInS2 has large birefringence and low absorption in the THz frequency region is judged to be a potentially more useful optical nonlinear material than the analogous compound LiGaO2.

APPLICATIONS:

l  Up-conversion of CO2-laser radiation image into near-IR or visible region

l  Different frequency generator in middle IR range (2-12 μm)

l  Optical parametric oscillator in 1-12 μm range with pump Al₂O₃: Ti

l  Frequency mixing in the middle IR region

l  For tunable solid-state lasers using OPO, pumped by Nd: YAG and other lasers in the range 1.2 - 10 μm

l  Broadband Mid-Infrared Optical Parametric Amplification