Nonlinear Phenomena in Complex Systems, 2026, Vol.29, No.2, pp.187-194

NONLINEAR PHENOMENA IN COMPLEX SYSTEMS
An Interdisciplinary Journal

2026, Vol.29, No.2, pp.187-194

The Photochromic Effect in Sillenite Crystals on Pulsed Laser Excitation

I. G. Dadziankou, A. L. Tolstik, and S. M. Shandarov

The work presents a theoretical model, including two different types of donors, for redistribution of charge carriers on optical excitation in the sillenite-family crystals. The model describes dynamics of the photochromic effect that is exhibited as a reversible change of the absorption factor on optical excitation of a crystal. Bismuth silicate crystals were used to study dynamics of the photoinduced absorption-factor variations under the effect of nanosecond laser pulses. Based on comparison of the experimental data and theoretical results, the observed transitions have been separated and the relation between probabilities of the transitions, populations of acceptor and donor levels has been determined. It has been shown that the dynamics of the induced absorption in the microsecond range is described by an exponential function, whereas the induced-absorption relaxation process in the millisecond range - by a hyperbolic function. Besides, the proposed model enables one to explain an increase of relaxation time in the millisecond range with growing of the exciting radiation wave length.

Key words: photorefractive crystals, bismuth silicon oxide, bismuth titanium oxide, light-induced effects, trapping levels

DOI: https://doi.org/10.5281/zenodo.21107304

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