UP-CONVERSION FLUORESCENCE OF HO3+ IN TEO2-BASED GLASSES

An upconversion fluorescence has been observed for the first time in tellurite glasses doped with Ho3+ at room temperature without using any sensitizing ions such as Yb3+. A 645 nm laser beam from Ar ion laser-pumped dye laser has been used as a pumping source for the stepwise excitation. The two-step excitation of upconversion fluorescence was confirmed by the quadratic changes of upconversion fluorescence intensity with the excitation power. The intensity of the upconversion fluorescence is relatively high; it reaches about half of the value for AlF3-BaF2-CaF2 glass containing the same amount of Ho3+, indicating that the present tellurite glasses are promising materials for upconversion laser.