Enhanced 1.53 Μm Fluorescence and Energy Transfer Mechanism in Tellurite Glasses Doped with Er3+/Ce3+/Yb3+

Tellurite glasses (TeO2–ZnO–La2O3) doped with Er3+, Er3+/Ce3+ and Er3+/Ce3+/Yb3+ have been prepared using the melt-quenching technique, and the absorption spectra, fluorescence and up-conversion emission spectra together with the differential scanning calorimeter (DSC) curves and X-ray diffraction (XRD) patterns were measured to evaluate the effects of Ce3+ and Yb3+ introduction on the 1.53µm band spectroscopic properties of Er3+, thermal stability and structural nature of glass hosts. The Judd–Ofelt intensity parameters Ωt (t=2,4,6), spontaneous emission probabilities, radiative lifetimes and branching ratios of several Er3+ transitions were calculated from the measured absorption spectra based on the Judd–Ofelt theory. The co-doping with Ce3+ was effective on the suppression of up-conversion emission of Er3+ owing to the phonon-assisted energy transfer: Er3+:4I11/2+Ce3+:2F5/2→Er3+:4I13/2+Ce3+:2F7/2, while the co-doping with Yb3+ had the effect of obviously increasing the Er3+ population at 4I11/2 level via the resonant energy transfer: Yb3+:2F5/2+Er3+:4I15/2→Yb3+:2F7/2+Er3+:4I11/2, both of which contributed the effective enhancement of 1.53µm fluorescence emission. The quantitative studies were carried out to elucidate the energy transfer mechanism by calculating the microscopic parameters and phonon contribution ratios. The glass transition temperature (Tg), crystallization onset temperature (Tx) and the difference ΔT(=Tx−Tg), which characterize the thermal stability of glass host, increased with the Ce3+ and Yb3+ co-doping and for all glass samples the value of ΔT is larger than 145°C. The glass structural nature was demonstrated from the measured XRD patterns with no sharp diffraction peaks. The results of the present work indicated that the prepared Er3+/Ce3+/Yb3+ co-doped tellurite glass is a potential material for developing broad-band and high-gain optical amplifiers and other optical devices.