PHOTON-GATED SPECTRAL HOLE-BURNING IN SRTIO3 CR3+

Persistent spectral holes were observed in the R-lines of SrTiO3:Cr3at 2 K. The hole burning mechanism was shown to be due to a two-photon or gated process, where a second optical excitation causes bleaching by photoionization of Cr3+. The trapping center responsible for the ho le burning is postulated to be an oxygen vacancy in the lattice associ ated with a Cr3+ ion. A series of samples reduced at different tempera tures was studied, and the hole burning efficiency was seen to be stro ngly dependent on reduction temperature.