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Updated: Oct 16, 2025

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Balanced infrared nonlinear optical performance achieved by modulating the covalency and ionicity distributions in
Bin-Wen Liu1, Xiao-Ming Jiang1, Shao-Min Pei1
1State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China. xmjiang@fjirsm.ac.cn.
Abstract:
The nonlinear optical (NLO) efficiency (d) and laser-induced damage threshold (LIDT) of a material are mainly determined by their covalency and ionicity, respectively, the incompatibility between which makes balancing the d and LIDT challenging in an IR NLO material. The topological feature (fractal dimension) of the electron localization function (ELF) map (distribution of covalency and ionicity) was evaluated for a series of NLO materials, and, phenomenologically, the fine mixing of covalency and ionicity will benefit a balanced d and LIDT. Chemical bonds with different interaction strengths were introduced simultaneously to mix the covalency and iconicity finely, and three new IR NLO sulfides, A2Ba3Li6Ga28S49 (A = K, 1; Rb, 2; Cs, 3), were obtained. They exhibit a strong NLO efficiency (1.9-2.1 × AgGaS2 at 1064 nm and 0.5-0.6 × AgGaS2 at 1910 nm) and high LIDTs (16.7-18.0 × AgGaS2), which fulfill the criteria of being promising IR NLO candidates. This study provides a new method for designing high-performance IR NLO materials based on the topological features of the ELF.
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