Linear and Nonlinear Optical Properties of K₃B₆O₁₀Br Single Crystal: Experiment and Calculation

The experimental and theoretical analysis of linear and nonlinear optical properties of K₃B₆O₁₀Br (KBOB), with a moderate birefringence that is suitable for UV coherent light generation and optical parametric oscillators, is presented in detail. The second-order nonlinear optical coefficients were measured by the Maker fringe method and the refractive indices dispersion curves were deduced by the minimum deviation technique at 16 different monochromatic sources from UV to NIR, and then the type I and type II phase-matching curves of second, third, and fourth harmonic generation (SHG, THG, and FHG) were calculated. Moreover, the correlations of crystallographic and crystallophysical axes were determined. On the basis of the density functional theory (DFT), the first-principles calculations have been employed successfully to study the structural and electronic properties of KBOB. In addition, to gain further insight into the structure–property relationship, the SHG density method was adopted to analyze the origin of the nonlinear optical response of KBOB