Fabrication and upconversion luminescence of Er3+/Yb3+ codoped TeO2-WO3-Na2O-Nb2O5-Al2O3 glass fibers

► We fabricate Er3+/Yb3+ codoped TeO2-WO3-Na2O-Nb2O5-Al2O3 glass fibers. ► We evaluate the upconversion luminescence of these tellurite fibers. ► The pump power dependent intensities were discussed. ► The Er3+/Yb3++co-doped tellurite fibers show an efficient upconversion process. ► We show that two photons are involved in the upconversion process.