NONLINEAR SINGLE CRYSTAL OF LITHIUM CHALCOGENIDES AND METHOD FOR ITS PREPARATION Russian patent published in 2021 - IPC C30B29/46 C30B11/04 G02F1/355 G02F1/37 

FIELD: crystallography.

SUBSTANCE: invention relates to lithium chalcogenide crystals for nonlinear optics. A nonlinear single crystal of lithium chalcogenides of the general formula Li_xAg_1-XGaSe₂, where x takes any value from 0.01 to 0.98 with a corresponding change in the spatial group from tetragonal I2d to rhombic Pna2₁ (at x=0.98), unit cell parameters 5.991<a<6.842 , 5.991<b<8.251 , 6.549<c<10.884 , volume 369.711<V<390.584 characterized by functional parameters: transparency range 0.37-19.6 microns, band gap at a temperature of 300 K 1.8-3.34 eV, birefringence value Δn>0.02, nonlinear coefficient 9.9-39.0 pm/V, optical destruction threshold 15-90 MW/cm² with a pulse duration of 6 ns, a repetition rate of 100 Hz, a wavelength of 1.064 microns. The method for obtaining a single crystal Li_xAg_1-XGaSe₂, where x takes any value from 0.01 to 0.98, consists in pre-synthesizing Li_xAg_1-XGaSe₂ compounds from elementary components Ag, Se, Ga (4N) and Li (2N) under conditions of ensuring a stoichiometric ratio of components, then growing a single crystal by the Bridgman method in a vacuum ampoule installed in an oven at a growth rate of 5 to 10 mm/day and an average axial temperature gradient of 10 to 20°C/cm and cool the oven at room temperature.

EFFECT: obtained crystals are transparent in a wide range of wavelengths and provide the realignment of visible and near-infrared laser radiation into the mid-IR range.

1 cl, 3 dwg, 1 tbl, 3 ex