Effects of GeO 2 concentration on the absorption and fluorescence behaviors of Yb 3+ in tellurite glasses

Abstract Yb 3+ -doped tellurite glasses exhibited largest absorption and emission cross sections. However, it is more valuable to achieve larger Stark splitting of Yb 3+ than improve the absorption and emission cross sections. In this work, we introduced a part of GeO 2 into tellurite glass matrix to enlarge the Stark splitting of Yb 3+ . The effects of GeO 2 concentration on the spectroscopic characteristic of Yb 3+ were systematically investigated. The stimulated absorption and emission cross sections increased to be 1.62 pm 2 and 0.88 pm 2 when the GeO 2 concentration up to 30 mol%, then decreased with the GeO 2 concentration further increased. The Stark splitting of Yb 3+ do not change until the GeO 2 concentration up to 30 mol%. The NIR fluorescence lifetimes of Yb 3+ drastically decreased from 850 μs to 385 μs with the GeO 2 concentration increasing, which was due to the increasing multi-phonon relaxation rate and reabsorption. Intense NIR fluorescence were observed when excited by the ultraviolet light, which can be ascribed to the energy transfer from the CTB of Yb 3+ -O 2- couple to Yb 3+ . The CTB showed a slight blue-shift from 338 to 313 nm with GeO 2 concentration increasing, which was ascribed to the size of the cation site would increase.