Boosting visible luminescence of Tb3+-activated ZBLAN fluoride glasses by Dy3+ co-doping

Tb3+ ions doped optical materials have emerged as gain media for green fiber lasers. Dy3+ ions were proposed as a sensitizer of Tb3+ ions in glasses to increase the excitation efficiency, yet a systematic understanding of the impact of Dy3+ doping on spectroscopic and physiochemical properties of glasses remains lacking. Here, using Tb3+/Dy3+ doped fluoride glass as a model system, we reveal that Dy3+ doping not only enhances Tb3+ emission intensity, but also increases the thermal stability of fluoride glasses. Detailed spectroscopic characterizations indicate that co-doping Dy3+ ions boosts visible luminescence intensity of Tb3+ ions in fluoride glasses due to sensitization of Tb3+ by Dy3+ ions. Importantly, we deeply research the energy transfer process, ascertain several important factors affecting energy transfer efficiency and propose optimal doping concentrations of Tb3+ and Dy3+ ions for visible emission. We envisage that our finding provides a new perspective for the synthesis of Tb3+-doped fluoride glasses with enhanced thermal stability, and may be extended for the fabrication of Tb3+-activated optical fibers.