Effect of Yb 3+ on the Structural and Visible to Near-Infrared Wavelength Photoluminescence Properties in Sm 3+ -Yb 3+ -Codoped Barium Fluorotellurite Glasses.

We report on the Sm 3+ and Sm 3+ :Yb 3+ -doped barium fluorotellurite glasses prepared using the conventional melting and quenching method. The spectroscopic characterisations were investigated with Raman and FTIR to evaluate the glasses' structural and hydroxyl (-OH) content. The Raman analysis revealed a structural modification in the glass network upon adding and increasing the Yb 3+ concentration from a TeO 3 trigonal pyramid to a TeO 4 trigonal bi-pyramid polyhedral. At the same time, the FTIR measurements showed the existence of -OH groups in the glass. Thus, under the current experimental conditions and nominal composition, the -OH group contents are too large to enable an effective removal. The near-infrared region of the absorption spectra is employed to determine the nephelauxetic ratio and bonding parameters. The average nephelauxetic ratio decreases, and the bonding parameter increases with the increasing Yb 3+ content in the glasses. A room temperature visible and near-infrared photoluminescence ranging from 500 to 1500 nm in wavelength and decay properties were investigated for glasses doped with Sm 3+ and Sm 3+ -Yb 3+ by exciting them with 450 and 980 nm laser sources. Exciting the Sm 3+ - and Sm 3+ -Yb 3+ -doped glasses by 450 nm excitation reveals a new series of photoluminescence emissions at 1200, 1293, and 1418 nm, corresponding to the 6 F 11/2 state to the 6 H J ( J = 7/2, 9/2, 11/2) transitions. Under the 976 nm laser excitation, a broad photoluminescence emission from 980 to 1200 nm was detected. A decay lifetime decreased from ~244 to ~43 μs by increasing the Yb 3+ content, ascribing to concentration quenching and the OH content.