Thermal Stability and Spectroscopic Properties of New Er³⁺/Yb³⁺-Codoped Tellurite Glasses

A series of new Er³⁺/Yb³⁺-codoped 70TeO₂--5Li₂O--(25-x)B₂O₃--xGeO₂ (TLBG, x=0, 5, 10, 15, 20mol%) glasses are prepared. The thermal stability and spectroscopic properties of TLBG glasses are studied. It is found that these glasses have the better thermal stability ((T_x-T_g)>150 °C) compared with 75TeO₂--20ZnO--5Na₂O (TZN) glass. The fluorescence full width at half maximum (FWHM) is about 77nm, while the emission intensity and the quantum efficiency of the ⁴I_13/2 level of Er³⁺ increase with the increasing GeO₂ content. The maximum quantum efficiency and stimulated emission cross-section of Er³⁺ calculated from the McCumber theory are 93.82% and 9.0×10^-21cm², respectively. The products of FWHM and σ^peak_e of Er³⁺ in TLBG glasses are larger than those in other reported glasses. The obtained data indicate that this kind of TLBG glasses is a promising candidate host material for Er³⁺-doped broadband amplifiers.