Dynamics of Light-Absorption Variations in a Bismuth-Silicate Crystal Induced by Laser Irradiation in the Visible Wavelength Range
The results of the experimental studies of the dynamics of the photo-induced optical absorption in a bismuth-silicate crystal subject to continuous laser irradiation with wavelengths of 532 and 655 nm are presented. The semiconductor-laser light beam with the wavelength λ = 655 nm causes the crystal bleaching at this wavelength, whereas its exposure to a shorter-wave irradiation from the optical-spectrum green region with a wavelength of 532 nm increases the optical absorption at both used wavelengths of 532 and 655 nm. The experimental results are interpreted using the theoretical model, which assumes that the crystal has deep defect centers of two types so that an electron at each of the above-mentioned centers can be in one of the states characterized by various photoionization cross sections.