Li₃VO₄: A Promising Mid-Infrared Nonlinear Optical Material with Large Laser Damage Threshold

Abstract

Laser damage threshold (LDT) and the second harmonic generation (SHG) effect have been considered as key parameters of infrared (IR) nonlinear optical (NLO) materials. Infrared NLO crystals with both large LDT and strong SHG efficiency are very scarce. The combination of the V5+ cations with d0 electrons and alkali metal Li+ cations generates an IR NLO material, low temperature phase Li3VO4. The single crystal of Li3VO4 with sizes up to 25 mm × 14 mm × 3 mm has been grown by the top-seeded solution growth method using the V2O5 flux in an open system in this work. The material exhibits a large LDT value of 125.5 MW/cm2, which is about 25 times that of AgGaS2. The inclusion-free Li3VO4 crystal is very favorable for improving the LDT. It also exhibits an excellent SHG response: 1.6 times that of AgGaS2, the benchmark IR NLO crystal at 2090 nm, and 9.5 times that of KDP, the benchmark UV NLO crystal at 1064 nm. Electronic structure and optical properties studies elucidate that the large NLO responses originate mainly from the polarities of the VO4 tetrahedra and partly from the LiO4 tetrahedra. Additionally, a superior crystal growth method, comparatively simple chemical composition, and wide transmission range enable Li3VO4 to possess much better comprehensive performances for practical mid-IR NLO applications.