Infrared nonlinear optical crystals, preparation method therefor, and applications thereof

Disclosed in the present invention are infrared nonlinear optical crystals, a preparation method therefor, and applications thereof. The infrared nonlinear optical crystals have a molecular formula as shown in the following: A 18 X 21 Y 6 M 48 , A being Ba, Sr or Pb, X being Zn, Cd or Mn, Y being Ga, In or Al, and M being S, Se or Te. The crystals belong to a trigonal system, and have a space group of R3. The crystal Ba 18 Zn 21 Ga 6 S 48 is an I phase matching nonlinear optical material, and in the granularity ranging from 150 μm to 210 μm, the powder frequency doubling strength and the laser induced damage threshold of the crystal are 0.5 times and 28 times of those of a commercial material AgGaS 2 respectively, other crystals have a same or similar structure and optical and other performance, have important application prospects in military and civil uses, and can be used in electro-optical countermeasures, resource exploration, space anti-missile purposes, communications and other aspects.