Spectroscopic properties of Tb 3+-doped fluoride glasses

Abstract

In this paper, the preparation is reported of a new family of Tb-doped fluoride glasses with the following composition: 30BaF 2 + 30InF 3 + 10ThF 4 + 9ZnF 2 + 20RF (where RF = LiF, NaF and KF). These glasses have been used for a systematic study on the optical absorption, excitation and photoluminescence spectral properties from the near UV to the NIR. On the basis of the measured values of densities and refractive indices, the dielectric constant, reflection losses, molar-refraction, Tb 3+ ion concentration in glasses, and several other physical properties were determined. From the measured absorption spectral intensities of five different states, the validity of the Judd-Ofelt model was examined in the evaluation of the intensities, transition probabilities, relaxation rates and radiative lifetime of the 5D 4 luminescent level. The lifetime of the 5 D 4 → 7 F j fluorescence was examined at both 300 K and 77 K and it was found it compared well with the theoretical value. The effects of the alkali cation change on the induced emission cross-section, quantum efficiency and branching ratios of this luminescent level based on the measured and computed fluorescence lifetimes were also studied.