Temperature dependent lifetime of Dy3+: 1.3 μm emission in Ge-As-S glass containing very small amount of Ga and CsBr

► Local structures of Dy3+ in Ge-As-S glass modified with small amount of Ga and CsBr. ► Uncommon temperature dependent lifetime of the 1.3 μm emission in these glasses. ► Competition between multiphonon relaxation rate and spontaneous emission rate. ► Interesting temperature dependent absorption cross-section spectra of these glasses.