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Title: Structural and optical properties on thulium-doped LHPG-grown Ta2O5 fibres
Author: Macatrão, M.
Peres, M.
Rubinger, C. P. L.
Soares, M. J.
Costa, L. C.
Costa, F. M.
Monteiro, T.
Franco, N.
Alves, E.
Saggioro, B. Z.
Andreeta, M. R. B.
Hernandes, A. C.
Keywords: Tantalum pentoxide
Rare earth doping
Issue Date: Feb-2009
Publisher: Elsevier
Abstract: Structural, spectroscopic and dielectric properties of thulium-doped laser-heated pedestal Ta2O5 as-grown fibres were studied. Undoped samples grow preferentially with a single crystalline monoclinic structure. The fibre with the lowest thulium content (0.1 at%) also shows predominantly a monoclinic phase and no intra-4f12 Tm3+ recombination was observed. For sample with the highest thulium amount (1.0 at%), the appearance of a dominant triclinic phase as well as intraionic optical activation was observed. The dependence of photoluminescence on excitation energy allows identification of different site locations of Tm3+ ions in the lattice. The absence of recombination between the first and the ground-state multiplets as well as the temperature dependence of the observed transitions was justified by an efficient energy transfer between the Tm3+ ions. Microwave dielectric properties were investigated using the small perturbation theory. At a frequency of 5 GHz, the undoped material exhibits a dielectric permittivity of 21 and for thulium-doped Ta2O5 samples it decreases to 18 for the highest doping concentration. Nevertheless, the dielectric losses maintain a very low value.
Peer review: yes
DOI: 10.1016/j.mejo.2008.07.033
ISSN: 0026-2692
Appears in Collections:DFis - Artigos
I3N-FSCOSD - Artigos

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