Upconversion Luminescence Research of Er~(3+)-doped Oxyfluoride Tellurite Glasses

The absorption spectra and upconversion luminescence spectra of Er3+-doped oxyflu-oride tellurite glasses were investigated, and upconversion luminescence mechanisms of Er3+ in oxyfluoride tellurite glasses were analyzed. The results show that the intense green (524 and 545nm) and red (655nm) emissions corresponding to the 2H9/2→4I15/2, 2H11/2→4I15/2,4S3/2→4I15/2, and 4F9/2→4I15/2 transitions of Er3+ ions, respectively, can be simultaneously observed at room temperature under 975 nm diode laser excitation. With increasing PbF2 concentrations, the intensity for the green emissions increases slightly, while the red emission intensity enhances much larger than the green emission intensities. There are two basic upconversion mechanisms: excited state absorption and energy transfer, and a two-photon upconversion process is assigned to the intense green and red emission, respectively.