Spectroscopic characterization of Tm3+:TeO2-K2O-Nb2O5 glasses for 2-μm lasing applications

► Spectroscopy of a new thulium-doped tellurite host Tm2O3:(0.70)TeO2-(0.15)K2O-(0.15)Nb2O5. ► Judd-Ofelt analysis and quantum efficiency measurements were performed. ► An emission cross section value of as high as 6.85×10−21 cm2 was measured for the 1860-nm band. ► Results reveal the potential of the glass for 2-μm laser development in bulk glass and fiber form.