Compositional effects on fluorescence lifetime of Dy3+ ions embedded in chalcogenide Ge-As-S glasses containing very small amount of Ga and CsBr

Abstract

We have investigated the fluorescence lifetimes of Dy3+: 1.3 mu m emission in the chalcogenide Ge-As-S glasses with different compositions but identically containing 0.5 mol% Ga and 0.5 mol% CsBr. The measured lifetimes turn out to be sensitive not only to the concentrations of Ga and CsBr but also to compositional variations in the Ge-As-S host glasses. The lifetime is enhanced conspicuously in glass of the S-sufficient compositions, relative to the stoichiometric GeS2-As2S3 composition, while this effect is not significant in the S-exact and S-deficient compositions. We employ Ga K-edge EXAFS analysis to support that the local structural environments of Ga in the modified chalcogenide glasses are closely correlated with the lifetime enhancement effect.