Optimized oriented seed growth and optical properties of high-quality LiInSe2 crystals

Mid-infrared (MIR) coherent light generated by nonlinear optical (NLO) materials is crucial for military and civilian applications. Among the MIR optical crystal family, the LiInSe2 (LISe) single crystal is a promising candidate due to its remarkable physical properties. Herein, a high-quality LISe crystal with the largest diameter of 31 mm was successfully grown by the Bridgman growth method using an oriented seed. The crystalline quality and optical homogeneity of LISe were demonstrated by high-resolution X-ray diffraction (HRXRD), Laue diffraction, and optical interferometry measurements, respectively. Additionally, a complete survey of the transmittance spectra, absorption coefficients, and refractive indices was systematically performed. Furthermore, we found that the absorption coefficients of LISe at 1.064 m can be obviously decreased after thermal annealing under LISe atmospheric conditions. More generally, our results will contribute significantly to the practical applications of LISe in the MIR technology field.