Investigation of the TeO/GeO Ratio on the Spectroscopic Properties of Eu-Doped Oxide Glasses for Optical Fiber Application.

This study presented an analysis of the TeO/GeO molar ratio in an oxide glass system. A family of melt-quenched glasses with the range of 0-35 mol% of GeO has been characterized by using DSC, Raman, MIR, refractive index, PLE, PL spectra, and time-resolved spectral measurements. The increase in the content of germanium oxide caused an increase in the transition temperature but a decrease in the refractive index. The photoluminescence spectra of europium ions were examined under the excitation of 465 nm, corresponding to F → D transition. The PSB (phonon sidebands) analysis was carried out to determine the phonon energy of the glass hosts. It was reported that the red (D → F) to orange (D → F) fluorescence intensity ratio for Eu ions decreased from 4.49 (Te0Ge) to 3.33 (Te15Ge) and showed a constant increase from 4.58 (Te20Ge) to 4.88 (Te35Ge). These optical features were explained in structural studies, especially changes in the coordination of Ge to Ge. The most extended lifetime was reported for the Eu doped glass with the highest content of GeO. This glass was successfully used for the drawing of optical fiber.