Abstract

We demonstrate experimentally that time evolution of light-induced absorption in Bi₁₂TiO₂₀ crystals exhibits complicated behavior at their sequential irradiation by incoherent light from two light-emitting diodes with the wavelengths of 660 and 505 nm. To interpret our results we propose a novel two-center model of light- induced changes in absorption considering a two-level structure for each defect center and the in-center transitions between inherent levels. Comparison of the experimental results with the theoretical model for Bi₁₂TiO₂₀ crystals with different stoichiometry leads us to the conclusion that the titanium vacancies may be considered as trap centers, which provide light-induced absorption.

© 2005 Optical Society of America