Light-induced infrared absorption in Ru-doped Bi/sub 12/TiO/sub 20/ single crystals

This paper presents measurements of light-induced near infrared absorption in Bi/sub 12/TiO/sub 20/ (BTO) crystals highly doped with Ru. According to the light-induced absorption dark decay measurements it is supposed that Ru creates two different levels: Ru/sup 3+/4+/ and Ru/sup 4+/5+/ located "more shallow" than the deep one with respect to the valence band. Each of these two levels has different contribution to the light-induced absorption and different thermal ionization rates /spl beta/, so the interaction between them can be neglected. After pump light illumination a redistribution of electrons from the deep into the shallow levels occurs and as a result absorption is changed, because the absorption cross-section is different for the deep and the shallow traps. On the basis of these preliminary experimental results the Ru-doped BTO crystal is proposed as a promising material for near-infrared photorefractive applications.