Fluorescence dynamics of Tb3+ and Tb3+/Ho3+ doped phosphate glasses

UV absorption and fluorescence analysis of Tb3+ in phosphate glass is carried out by Judd-Ofelt method with emphasis on the D-5(4) -> F-7(5) lasing transition. Branching ratios, peak emission cross-sections for D-5(4) -> F-7(j) (j = 3, 4, 5 and 6) transitions and lifetime of D-5(4) level of Tb3+ are calculated using Judd-Ofelt intensity parameters. Furthermore, fluorescence dynamics of the D-5(4) level of Tb3+ ion in phosphate glasses co-doped with Ho3+ were experimentally investigated with classical Forster-Dexter model for direct cross-relaxation type energy transfer between Tb3+ (donor)and Ho3+ (acceptor). The energy transfer rates between Tb3+ and Ho3+ in phosphate glasses were calculated on the basis of experimental measurements. These measurements were performed for 1 wt.% of Tb3+ and Ho3+ concentration ranging from 0 to 3 wt.%. The results show that energy transfer occurs between the D-5(4) terbium and F-5(3) holmium levels and is a phonon-assisted dipole-dipole interaction. (C) 2007 Elsevier B.V. All rights reserved.