We present the results of experimental studies of the dynamics of the photoinduced optical absorption
in a bismuth silicate crystal subject to continuous laser irradiation with wavelengths of
532 and 655 nm. The semiconductor-laser light beam with the wavelength λ = 655 nm causes
the crystal bleaching at this wavelength, whereas its exposure to a shorter-wavelength irradiation
from the optical-spectrum green region with a wavelength of 532 nm increases the optical
absorption at both 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 these centers can be in one of the states characterized by different
photoionization cross sections