Concentration effects on the optical spectroscopic properties of Er3+- doped TeO2-Nb2O5-ZnO vitreous system

A detailed spectroscopic study of erbium doped tellurite glasses having the basic molar composition (70TeO2 -10Nb2O5-20ZnO) and containing different concentrations of Er2O3 (x = 0.5, 1.5, 2.5, 3.5) (in wt %) is presented in this work. These glasses were prepared according to the conventional melt-quenching method. Using optical absorption data and Judd-Ofelt theory, several spectroscopic parameters such as optical band gap energy, Urbach energy, transition probabilities (AJ-J′), radiative lifetimes (τrad), branching ratios (β) and integrated emission cross-sections (σem) for the different 4f-transitions were estimated for different Er2O3 contents. Photoluminescence spectroscopy measurements were performed for the different samples at room temperature using 488 nm excitation wavelength of an argon-ion laser. The influence of Er2O3 concentration on the lifetime of 4I13/2 level and line shape of the infrared emission at 1532 nm was analyzed using Mc Cumber theory and the observed results were correlated with the glass structure. Our results were compared to those existing in recent literature for others TeO2 based glasses. It was found that the effective bandwidth is larger and the optical gain coefficient and the quality factor are higher than those obtained for others vitreous systems, which suggests that the proposed glasses can be nominated as suitable host material for new Er3+doped broad-band optical amplifiers and the developments of optical devices.