title: Temperature-dependent photoluminescence spectra of Er-Tm codoped calcium boroaluminate glasses.
abstract: The temperature dependence of photoluminescence (PL) spectra of Er-Tm codoped calcium boroaluminate (CABAL) glasses with different dopant concentrations was investigated under 15-298 K, by pumping at 795 nm. The intensities of three band emissions located at 1.46, 1.53, and 1.80 μm decreased monotonically when increasing the temperature from at lower concentrations. However, the emissions peaked at 1.80 μm increase with the increasing temperature at higher concentrations. This was attributed to the increasing of cross relaxation (CR) resulting from the high doping concentration of Tm ions. This was evidenced by the much shorter fluorescence lifetime of 56 μs for the 3F4 emission due to 3F4→3H6 transition for the CABAL glass codoped with 2.00 mol.% Tm2O3, in comparison with 185 μs for that of 0.2 mol.% Tm2O3. The energy transfer (ET) and CR processes between Er3+ and Tm3+ ions have been discussed at different doping concentrations and operating temperatures. The nonexponential character of the decays of 4I(13/2) and 3H4 with the increasing concentration indicated the occurring of a dipole-dipole quenching processes in the framework of a diffusion-limited regime. The average critical distances of CR between Tm3+ ions and ET between Er3+ and Tm3+ ions were approximately 1 nm.
authors.affiliation: SHU-SolarE R&D Laboratory, Department of Physics, College of Sciences, Key Laboratory for Material Microstructures of Shanghai University, Shanghai University, Shanghai, China. drfeixu@gmail.com
authors.forename: Fei
authors.initials: F
authors.lastname: Xu
authors.forename: Lingling
authors.initials: L
authors.lastname: Zheng
authors.forename: Mingzhu
authors.initials: M
authors.lastname: Li
authors.forename: Fang
authors.initials: F
authors.lastname: Lu
authors.forename: Zhongquan
authors.initials: Z
authors.lastname: Ma
authors.forename: Zuimin
authors.initials: Z
authors.lastname: Jiang
authors.forename: Pinghua
authors.initials: P
authors.lastname: Zhou
authors.forename: Jianwei
authors.initials: J
authors.lastname: Shi
authors.forename: Yu
authors.initials: Y
authors.lastname: Pu