Effect of Na2O concentration on the lifetime of Er3+-doped sodium silicate glass

Abstract

A set of sodium silicate glass matrices with different Na₂O concentrations and doped with constant Er³⁺ content were synthesized by fusion. The influence of Na₂O on the luminescence of Er³⁺ ions in the region of 1.53 μm was studied. Samples were characterized by optical absorption (OA), time and energy resolved photoluminescence and Fourier Transform Infrared (FTIR). Sodium oxide concentration controls the absorption of OH radicals. FTIR showed a decrease in OH radicals, which is correlated with an increase in the lifetime of the transition at approximately 1.53 μm. However, a decrease in sodium concentration implies increasing interaction between the silicon network and Er³⁺ ions, thereby increasing non-radiative energy transfer from Er³⁺ ions to SiO₄ structures. The gain in the lifetime of this transition (∼6.9 ms) was obtained for the sample with the highest silicon concentration and is comparable with the well-known YAG system. Molecular dynamic results show that a reduction in non-bridging oxygen species occurs as Na₂O concentration decreases, which explains the reduction in OH radical absorption obtained in the experimental results.