Optical Absorption and Luminescence of Gd3Ga5O12:Cr,Mg Epitaxial Films

The optical absorption, emission spectra and luminescence decay kinetics under photoexcitation of Gd3Ga5O12 (GGG) garnet epitaxial films doped with Cr3+ ions and co-doped with Cr3+ and Mg2+ ions have been investigated. Luminescence of the GGG:Cr films due to T-4(2) -> (4)A(2) and E-2 -> (4)A(2) transitions in Cr3+ ions have been observed. Increase of the activator ions concentration has an influence on the intensity and decay time of Cr3+ ions photoluminescence. Introduction of the magnesium ions leads to partial transformation of chromium valence state (Cr3+ -> Cr4+) and to the appearance of a broad absorption band with the maximum at 860 nm. The narrow lines with luminescence maxima at 704 and 706 nm have arisen in the highly doped GGG:Cr,Mg films.