Nonlinear optical crystals are an important optoelectronic information functional material, playing an increasingly important role in modern technologies such as frequency conversion, optical parametric oscillation, electro-optic modulation and communication. At present, nonlinear optical crystals capable of producing visible and ultraviolet light, such as KTiOPO4 (KTP), LiB3O5 (LBO) and CsLiB6O10 (CLBO), have been able to meet practical applications. In the infrared range, although there are relatively mature commercial crystals such as AgGaS2 and ZnGeP2, it is difficult to grow a single optical waveplate manufacturer with high optical quality, and its low laser damage threshold and severe two-photon absorption limit its wide application. Therefore, the exploration of infrared nonlinear optical materials with excellent performance has become an important direction of photoelectric functional materials.
After systematic research, the researchers found that M2LiVO4 (M = Rb, Cs) is two excellent mid-infrared nonlinear efficient optical grade special shape sapphire optics materials. Both of these compounds have a wide transmission range, a large nonlinear coefficient (powder frequency doubling Rb2LiVO4 is 4 x KDP and Cs2LiVO4 is 5 x KDP, and both are phase matched) and a strong laser damage threshold. It is worth mentioning that these two compounds are all molten compounds of the same composition, and it is easy to grow large-sized single crystals with high optical quality, which means that the two crystals have potential application value in the mid-infrared band. In addition, through first-principles calculations, the researchers found that in the structural motifs of the two compounds, the VO4 group is the main source of the doubling effect of these two compounds high gain YAG laser crystal.