Optical transitions of Er 3 + ion in two tellurite glasses of molar composition 75TeO 2 :12ZnO:10Na 2 O:2PbO:1Er 2 O 3 and 75TeO 2 :12ZnO:10Na 2 O:2GeO 2 :1Er 2 O 3 were investigated. The measured absorption and emission spectra were analysed by Judd-Ofelt and McCumber theories, in order to obtain radiative transition rates and stimulated emission cross sections. It was found that these glasses have high and broadband absorption and stimulated emission cross sections at 1.5 μm. For the metastable 4 I 1 3 / 2 level, by comparing the measured lifetime with the calculated radiative decay time, quantum efficiency higher than 80% was found.