Optical Properties, Structural Homogeneity, and Defect Centers of Double-Doped LiNbO3:Zn:Mg Single Crystals Obtained Using Different Technologies

https://doi.org/10.1134/S2075113324701648

Features of the defect structure of a nominally pure LiNbO_3stoich crystal and double-doped LiNbO₃:Zn:Mg (3.45:1.41 mol %) and LiNbO₃:Zn:Mg (3.45:1.22 mol %) single crystals have been studied using Raman spectroscopy, infrared absorption spectroscopy, photoluminescence, laser conoscopy, and photoinduced light scattering. The material for the study has been obtained using homogeneous and direct doping technology. It has been shown that double-doped LiNbO₃:Zn:Mg crystals obtained using different technologies have high resistance to damage by laser radiation. However, the LiNbO₃:Zn:Mg (3.45:1.22 mol %) crystal obtained by direct doping technology is characterized by lower compositional uniformity compared to the LiNbO₃:Zn:Mg (3.45:1.41 mol %) crystal obtained by homogeneous doping technology. Raman spectra have showed that the features of the defect structure of double-doped LiNbO₃:Zn:Mg crystals are largely determined by the magnesium impurity. This may be the reason that the influence of the ordering mechanism of magnesium cations (~1.22–1.44 mol %) prevails over the influence of the disordering mechanism of zinc cations (~3.45 mol %) on the features of the structural units of the cation sublattice. It has been found that the lowest concentration of OH groups and photoluminescence intensity in the near-IR region is characteristic of the LiNbO₃:Zn:Mg (3.45:1.41 mol %) crystal obtained by homogeneous doping technology.