The compatibly large nonlinear optical effect and high laser-induced damage threshold in a thiophosphate CsInP2S7 constructed with [P2S7]4- and [InS6]9-

It is challenging to cooperatively improve the nonlinear optical (NLO) efficiency and the laser-induced damage threshold (LIDT). This work reports a novel IR NLO materials CsInP2S7 (CIPS) designed by combination the strategies of alkali metals substitution and microscopic NLO units PS4 introduction based on AgGaS2. CIPS was composed of strongly distorted [InS6]9- octahedra and [P2S7]4- dimers constructed by corner-sharing [PS4]3-, which increase the NLO efficiency and decrease thermal expansion anisotropy simultaneously. Compared with AgGaS2, CIPS exhibited strong phase matchable NLO response ca. 1.1 × AGS@2.1 µm, high LIDT ca. 20.8 × AgGaS2, and IR transparency up to 15.3 µm. Structural analysis and theoretical investigation confirmed that large SHG effect and ultrahigh LIDT of CIPS originated from the synergistic contribution of [InS6]9- octahedra and [P2S7]4- dimers. These results indicate that CIPS is a promising NLO candidate in the mid-IR region, and this study provides a new approach for developing potential NLO-LIDT compatible materials.