Lithium Thioindate (LiInS2 or LIS) is a remarkable ternary semiconductor known for its unique crystallization with mm2 symmetry. This advanced material boasts a large nonlinear optical (NLO) coefficient, positioning it closely alongside other notable compounds such as AgGaS2 and AgGaSe2, albeit with distinct crystal structures. One of the standout features of LiInS2 is its high laser damage threshold, coupled with a broad transparent wavelength range.

The transparency range of LiInS2 spans from 0.5 to 8 μm, making it an exceptional choice for mid-infrared NLO applications. Additionally, LiInS2 is pyroelectric, and its electro-optical parameters make it an effective material for various electro-optical applications. The ability to achieve three-frequency collinear phase matching, along with its large birefringence and low absorption in the THz frequency region, further enhances its potential as a superior optical nonlinear material compared to similar compounds like LiGaO2.

LiInS2's unique properties make it an invaluable asset in the field of nonlinear optics. Its large nonlinear optical coefficient and high laser damage threshold enable it to perform efficiently in demanding environments. The wide transparency range enhances its versatility, allowing it to be used in a variety of optical applications. Furthermore, its pyroelectric nature and favorable electro-optical parameters open up possibilities for innovative uses in electro-optical devices. The combination of these characteristics positions LiInS2 as a leading material in the development of advanced optical technologies.