The effect of Er3+- ion concentration on the Er3+ : 4I13/2 → 4I15/2 transition in tellurite glasses

The effect of Er3+ concentration on the Er3+ : (4) I-13/2 --> I-4(15/2) emission in tellurite glasses has been investigated. The full width at half-maximum increased with the increasing concentration of Er2O3 in tellurite glasses. The effect of local structure of Er3+ ions and related spectroscopic changes are taken into account to explain the line broadening. Inhomogeneous broadening due to the distribution of crystal field around the Er3+ ion has little effect on the absorption spectra. Highly efficient energy trapping between the ions was identified from the time-resolved analysis of the fluorescence decay and is found to be responsible for the extended lifetime at intermediate concentrations of Er3+ ions in tellurite glasses. The effect of temperature on spectral line shape has been determined for analysing the contribution of Boltzmann population on line broadening. The increased population of the overlying Stark sublevels at the I-4(13/2) energy level via direct pumping and/or interaction between Er3+ ions were also found to be significant for enhancement in spectral line shape at higher concentrations of Er3+ ions in tellurite glasses. It was observed that at higher concentrations of Er3+ ions in glass also enhance the local symmetry of ions, which is apparent from the absorption band of the Er3+ : I-4(15/2 -->) H-2(11/2) hypersensitive transition.