Investigation of the TeO(2)/GeO(2) Ratio on the Spectroscopic Properties of Eu(3+)-Doped Oxide Glasses for Optical Fiber Application

This study presented an analysis of the TeO(2)/GeO(2) molar ratio in an oxide glass system. A family of melt-quenched glasses with the range of 0–35 mol% of GeO(2) 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 (7)F(0) → (5)D(2) transition. The PSB (phonon sidebands) analysis was carried out to determine the phonon energy of the glass hosts. It was reported that the red ((5)D(0) → (7)F(2)) to orange ((5)D(0) → (7)F(1)) fluorescence intensity ratio for Eu(3+) 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 ([4])Ge to ([6])Ge. The most extended lifetime was reported for the Eu(3+) doped glass with the highest content of GeO(2). This glass was successfully used for the drawing of optical fiber.