Spectroscopic properties and external quantum yield of Sm3+ doped germanotellurite glasses

•Sm3+ doped germanotellurite glasses with multi-channel emissions were prepared.•High asymmetry and covalent environment has been identified in the glass system.•Multi-peak red fluorescence is efficiently extracted from the optical glasses.•Quantum efficiency and quantum yield are deduced to be 82.5% and 6.0%.

Sm3+ doped germanotellurite glasses (NZPGT) with maximum phonon energy of 793 cm−1 have been prepared and characterized. Judd-Ofelt parameters Ωt (t=2, 4, 6) have been calculated to be 3.52×10−20, 4.70×10−20 and 1.90×10−20 cm2, respectively. Large value of Ω2 indicates a high asymmetry and covalent environment around Sm3+ in the glass system. The maximum stimulated emission cross-section of the dominant transition 4G5/2→6H9/2 peaking at 645.0 nm was derived to be 10.00×10−22 cm2, predicting that the red fluorescence emission can be efficiently extracted from the optical glasses. The internal quantum efficiency and external quantum yield of 0.4 wt% Sm2O3 doped NZPGT glasses were deduced to be 82.5% and 6.0%, respectively. The results demonstrate that Sm3+ doped NZPGT glasses are a potential candidate for developing tunable visible lasers, compact light sources and solid-state display devices.