Upconversion properties of Er³⁺/Yb³⁺ co-doped TeO₂--Nb₂O₂--Li₂O glasses

The Er³⁺/Yb³⁺ co-doped TeO₂--Nb₂O₅--Li₂O glass is prepared by conventional melting method, and its upconversion spectra are measured. The intense green upconversion luminescence upon excitation with a 976nm laser diode is observed with the naked eyes. The dependence of luminescence intensity on the ratio of Yb³⁺/Er³⁺ is discussed in detail, and the relationship between the ratio of green luminescence intensity to red luminescence intensity and the ratio of Yb³⁺/Er³⁺ is also studied. The luminescence intensity increases with the ratio of Yb³⁺/Er³⁺ increasing. The ratio of Yb³⁺/Er³⁺ plays a more important role than the concentration of Er³⁺ in determining the upconversion luminescence intensity. The ratio of green luminescence intensity to red luminescence intensity reaches a maximum when ratio of Yb³⁺/Er³⁺ is 3. Thus the glass could be one of the potential candidates for LD pumping solid-state lasers.