The effect of Er³⁺-ion concentration on the Er³⁺ : ⁴I_13/2 → ⁴I_15/2 transition in tellurite glasses

Abstract

The effect of Er³⁺ concentration on the Er³⁺ : ⁴I_13/2 → ⁴I_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 ⁴I_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⁺ : ⁴I_15/2 → ²H_11/2 hypersensitive transition.

Acknowledgements

The authors acknowledge the support from the Engineering and Physical Science Research Council (GR/R31454/01), Nortel Networks at Harlow in Ipswich (UK), and the Korean Science and Engineering Foundation.