Optical characteristics and intensity parameters of Sm³⁺ in GeO₂, ternary germanate, and borate glasses

Absorption and fluorescence spectra of Sm3+ were measured in GeO₂, ternary germanate, and borate glasses. From these the intensity parameters were calculated by use of the Judd-Ofelt formula. Visible emission and decay times from the⁴G_5/2 level and its relative quantum efficiencies were measured The quantum efficiencies (QE) of the fluorescence in ternary germanate was higher by a factor of 20 than in GeO₂, The small QE in GeO₂, is explained by cross-relaxation between neighboring Sm³⁺ ions. The later process in hindered by the change in glass structure in the presence of modifier ions. A similar effect is observed in other glasses such as borate, where the addition of modifiers increases the QE of fluorescence.