International Ukrainian-French Agreement

“Chalcogenide nonlinear crystals for controlling the shape and propagation of laser irradiation pulses”

(principal investigator - Doctor of Sciences in Physical and Mathematical Sciences, Professor Oleksandr Hrabar)

Duration of the project: November 2021 – December 2021

Purpose: to develop new media and methods for effective control of the group velocity of laser pulses propagation and form of their wavefront with different type singularities based on nonlinear properties and optical anisotropy of doped chalcogenide crystals.

Result: monocrystalline samples of Sn2P2S6 single crystals with high optical quality and significant dimensions were grown, on the basis of which the phenomenon of conical diffraction of laser radiation was studied for the first time in order to develop new methods of controlling the spatial intensity and polarization of focused rays. The photorefractive effect in Sn2P2S6 crystals under pulsed excitation by an IR laser with a wavelength of 1064 nm was studied for the first time, and a significant increase in the two-wave interaction coefficient in comparison with the continuous mode was revealed. An optical scheme for slowing down the group velocity of nanosecond laser pulses was implemented and its parameters were investigated. The study of optical self-focusing in Sn2P2S6 crystals, undoped and doped with Sb, estimated the value of cubic optical nonlinearity and concluded that there are slow local photoinduced changes in the refractive index in these crystals.