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

The lifetime of 1.3 μm emission from Dy3+-doped Ge–As–S glass containing very small amount of Ga and CsBr reveals interesting temperature dependence; with the addition of Ga/CsBr up to ∼0.2 mol% the lifetime decreases with increasing temperature. When the concentration of Ga/CsBr reaches ∼0.3 mol%, however, the lifetime remains relatively constant regardless of temperature change. For further addition up to ∼0.5 mol%, the lifetime increases as temperature rises. This uncommon behavior is explained through our understanding of the different temperature dependences of multiphonon relaxation and spontaneous emission rates associated with the thermally coupled Dy3+: (6H9/2, 6F11/2) manifolds in our modified chalcogenide glass.