Spectroscopy and upconversion of Dy3+ doped in sodium zinc phosphate glass

Optical absorption and fluorescence spectra of Dy3+ doped in sodium zinc phosphate glasses have been reported. Judd-Ofelt theory has been applied to analyze the spectra and determine the optical parameters such as transition probabilities, radiative lifetime, stimulated emission cross-section, etc. The fluorescence intensity of Dy3+ corresponding to 4F9/2-->6H13/2 transition increases with increasing concentration of Dy3+ but at higher concentrations, concentration quenching is observed. The radiative lifetime of the 4F9/2 level at 1 mol% concentration of Dy3+ in this host is found to be 541 micros. Emission corresponding to 4F9/2-->6H13/2 transition (570 nm) is observed on excitation with NIR radiation due to upconversion. An attempt is made to explain this observation.