Optical studies of Dy3+ doped tellurite glass: Observation of yellow-green upconversion

Optical absorption and fluorescence spectra of Dy3+ doped tellurite glass have been studied and Judd-Ofelt theory has been used to derive its optical properties. The effect of temperature on the fluorescence yield and fluorescence quenching for higher concentrations of Dy3+ has been studied and the mechanism involved discussed. It is found that the fluorescence intensity is larger at lower temperature. The lifetime of the F-4(9/2) level has been measured and found to decrease with concentration as well as temperature. Intense upconversion has also been observed in the yellow-green region when pumped with NIR (similar to 862 nm) radiation. An explanation of the same involving energy transfer is offered. (c) 2005 Elsevier B.V. All rights reserved.