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

The tellurite fibers based on glasses with the composition TeO2–WO3–Nb2O5–Na2O–Al2O3–Er2O3–Yb2O3 were fabricated by the rod-in-tube technique using a Heathway drawing tower. The upconversion luminescence of Er3+/Yb3+ codoped tellurite glass fibers under 980 nm excitation were investigated. The Er3+/Yb3+co-doped tellurite fibers show an efficient up-conversion process in comparison with the Er3+-doped tellurite fibers. The pump power dependent intensities were discussed, which showed that two photons are involved in the upconversion process.