UV-induced acoustooptics of matrices containing BaHf(BO₃)₂ microcrystallites embedded into olygoetheracrylate photopolymer

UV-induced acoustooptics was explored for BaHf(BO₃)₂ microcrystallites with sizes varying within 5–30 μm range. The titled microcrystallites were embedded into the polymer matrices. The results were analyzed using both experimental optical as well as theoretical DFT approach. The measurements were done for principal acoustical frequencies: 0.5 MHz, 1 MHz, 2 MHz, and 3 MHz. The acoustical waves were excited by an electromechanical LiNbO₃ piezoceramics transducers from acoustical generator. We explored dependence of the acoustooptical efficiency versus the photoinducing laser beam power, angle between the beams, acoustical power light polarization and temperature. We explored variation of the acoustooptical efficiency at 1150 nm probing cw He-Ne laser wavelength under influence of pulsed nitrogen laser at wavelength 371 nm working in the 7 ns regime with frequency repetition 6 Hz at power densities up to 900 MW/cm². Existence of some optimal conditions at about 1 MHz and UV photoinduced power equal to about 0.8 MW/cm² was found. The spatial acousooptical gratings formation was observed. The DFT simulations of the charge density in main structural fragments under photoinducing UV beams is presented and principal role of the BO₃ structural fragments is established. This is confirmed by crystallochemistry analysis. The phenomenological description is also presented. - Graphical abstract: Principal relation between the crystallochemistry and acoustically induced charge density space distribution changes. UV induced acoustooptical behaviours. - Highlights: • UV-induced increase of acoustooptics of BaHf(BO₃)₂ microcrystallites shown. • Principal role of the crystalline nano-interfaces is shown. • BO₃ fragments play principal role.