CC BY
6LM-O-17
LASER-MATTER INTERACTION
Excitation of Rare-Earth Ions Luminescence in Glasses by Satellites of
Raman Scattering
G. Malashkevich1, V. Kouhar1, A. Sukhodola1, T. Khottchenkova1, N. Golubev2, M. Ziyatdinova2, V. Sigaev2
1 - B.I. Stepanov Institute of Physics of the National Academy of Sciences of Belarus, Minsk, 220072, Belarus 2 - D.I. Mendeleev University of Chemical Technology, Moscow, 125047, Russia Main author email address: g.malashkevich@ifanbel.bas-net.by
It was recently reported [1] about the luminescence of Yb3+ ions in phosphate glasses excited by laser radiation with \xc = 808 nm which falls outside the 2F7/2 ^ 2F5/2 absorption band of these ions. This effect was explained by the formation of a continuum of the defect centers with the excited states in the field of transparency of a matrix and transfer of excitations from them on the rare-earth activator [2]. Such interpretation for a number of reasons, which are analyzed in the present study, does not seem to be correct. Therefore, we synthesized fused multicomponent glasses and also silica sol-gel ones and studied the luminescence of rare-earth ions (Tb3+ and Yb3+) under laser excitation outside their absorption bands. As a result, we found that the dependence of the ions luminescence intensity on the energy gap between the incident quantum and the metastable state of the rare-earth ions excited by it in the glasses correlates with the intensity in the Raman spectrum of the used glass matrices (Fig.).
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a ■
u 1=
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Fig. Absorption (black curve) and luminescence spectra of glasses composition (mol %) 10Tb2O3-30Al2O3-60B2O3 (a) and 2Yb203-8Y203-30Al203-60B203 (b) at different A,exc (they are marked by arrows, the color of which coincides with the color of the corresponding luminescence spectrum), reduced to the same energy of the excitation pulse, and
the Raman spectrum of the matrix (insets).
This correlation made it possible to conclude that the detected effect is due to the emission-free transfer of excitations from Stokes satellites of Raman scattering to the rare-earth activator or, in other words, to the exchange of an incident light quantum for quanta corresponding to excitation of the rare-earth activator and the optical phonon. In this case, the latter can be caused both by vibrations of the matrix structural groupings and vibrations of impurity oscillators, in particular, by hydroxyl (OH-) groups. It is noted that for Yb-containing phosphate glasses such excitation is possible not only for isolated Yb3+ ions, but also through the excited state of paired Yb-Yb centers. Some possibilities of practical use of the described effect are considered.
[1] A.S. Pinheiro, A.M. Freitas, G.H. Silva, M.J.V. Bell, V Anjos, A.P. Carmo, N.O. Dantas, Laser performance parameters of Yb3+ doped UV-transparent phosphate glasses, Chem. Phys. Letters, vol. 592, pp. 164-169, (2014).
[2] W. Stambouli, H. Elhouichet, B. Gelloz, M. Ferid, N. Koshida, Energy transfer induced Eu3+ photoluminescence enhancement
in tellurite glass, J. Lumin., vol. 132, pp. 205-209, (2012).
