Quenching behavior of Sm3+ doped lanthanum aluminosilicate glasses

In this paper we report on the fluorescence quenching behavior of Sm3+ doped lanthanum alumino silicate glasses in dependence of the Sm3+ concentration and chemical composition of the glasses. In general, lanthanum alumino silicate glasses offer relatively low intrinsic Sm3+ fluorescence lifetimes between 2.3 and 2.7 ms. Independently on the doping concentration, the lifetime decreases with increasing refractive index and increasing lanthanum concentration of the glasses. For a low doping concentration of 0.1×1020 Sm3+ per cm3 (approx. 0.025 mol% Sm2O3) the measured fluorescence lifetimes are very close to the radiative lifetimes which were calculated using the Judd-Ofelt analyses. For higher doping concentrations, such as 1×1020 and 3×1020 Sm3+ per cm3, concentration quenching becomes obvious. For these higher concentrations, the non-radiative relaxation of the excited state can be seen as a mixture of cross-relaxation processes and OH− quenching. Both processes mainly occur at higher concentrations and do not influence the fluorescence decay at low Sm3+ concentrations. By contrast, the maximum phonon energy of the glass network does not affect the radiative relaxation of Sm3+ at all.