A.V. Uklein

Photoinduced refractive index variation within picosecond laser pulses excitation as the indicator of oxyorthosilicates single crystals composition modification

For the first time, the diagnostics of oxyorthosilicates single crystals based on self-action of picosecond range laser pulses at 1,064 nm (1.17 eV) has been performed. High sensitivity of the photoinduced refractive index variation to the substitution of the Lu atoms by Gd in the LSO/LGSO crystalline host as well as to the admixture of Ce was found. The effect can be explained with different electron detrapping-recombination process efficiencies due to the resonant electron excitation from the deep traps in the gap attributed to intrinsic oxygen vacancies.

The Effect of Sintering Temperature on Linear and Nonlinear Optical Properties of YAG Nanoceramics

Recent improvements in powder synthesis and ceramics sintering made it possible to fabricate high-quality optical materials. The work is devoted to the structural and optical characterization of the (\({Y_3}{Al_5}{O_{12}}\), YAG) ceramics prepared by high-pressure low-temperature technique. The structural properties of the studied ceramic samples was obtained by X-ray diffraction. The studies of the total and in-line transmittance as well as optical scattering indicatrices were performed in visible and NIR ranges. The scatterer size \(\sim200\) nm was estimated by Rayleigh–Gans–Debye model. It was shown that the studied samples demonstrate high transparency at 1064 nm. The nonlinear optical characterization of the samples was done by the self-action of the picosecond laser pulses at 1064 nm. The measured nonlinear optical response (\( \operatorname{Im}({{\chi }^{(3)}})\,\sim \,{{10}^{-11}}\,\text{esu} \) esu) showed significant dependence on the sintering temperature variation.

Impact of Water Adsorption on Nonlinear Optical Properties of Functionalized Porous Silicon

The porous silicon (PS) surface modification diagnostics due to functionalization and water adsorption/desorption processes were provided by the self-action effects of picosecond range pulsed laser radiation at 1064 nm. It was shown that the PS surface functionalization—oxide removal, alkylation, and oxidation—resulted in a refractive nonlinear optical (NLO) response sign turn to self-focusing (Δn>0) versus the self-defocusing (Δn<0) observed in the aged PS. The sensitivity of the proposed technique was revealed to water adsorption/desorption from the chemically oxidized PS interface. For the dried PS, the self-defocusing effect with corresponding NLO cubic susceptibility Re(χ(3))∼−4.7·10−9 esu was observed versus the self-focusing one (∼5·10−8 esu) for the PS positioned in saturated water vapor at room temperature. The obtained results demonstrate high sensitivity and wide versatility of the proposed readout technique based on pulsed laser radiation self-action at 1064 nm to the PS surface modification monitoring/diagnostics applications.

Impact of Merocyanine Dye Concentration in Ultrathin Polymer Films on Nonlinear Optical Response Due to the Aggregation Effect

Nonlinear optical properties of thin films of the organic merocyanine dye derived from the class of malonodinitrile dyes, as well as its solid guest-host systems based on polymethyl methacrylate are studied. The optical absorption spectra of films with different dye concentrations and of the dye solutions in non-polar solvents are measured. The scattering indicatrices of films are presented. The films demonstrated the efficient photoinduced variation of the refractive index under the pulsed and continuous wave laser excitations. A nonlinear optical response of films under the picosecond range pulsed laser excitation points to the aggregation effects at the 10-wt.% dye concentration and higher.