Spectroscopic properties of Er3+ doped novel tellurite glass for 1.5 μm amplification

Optical spectroscopic properties of Er³⁺ doped tellurite glass, 70TeO₂-15GeO₂-10Nb₂O₅- 5Li₂O (TGNL) and 90TeO₂-2ZnO-8PbO (TZP), were investigated for C-band optical amplification. The intensity parameters Ω_t (t=2,4,6), the radiative rates, the branching ratios and the fluorescence lifetimes were calculated for Er based on the experimental absorption spectra and Judd-Ofelt theory. Among three Ω_ts, the Ω₂ value was comparatively large in Er³⁺ doped TGNL glass while the Ω₄ and Ω₆ values are similar to other TeO₂-based glasses. The large Ω₂ value is probably ascribed to the low asymmetry at the Er + sites. The gain coefficient of TGNL and TZP glasses was estimated to be 0.646 and 0.671 cm with the Er³⁺ concentration is 0.760 × 10²⁰ cm^-3 and 0.849 × 10²⁰ cm³, respectively. The advantage of TGNL and TZP glasses over other glasses has been discussed.