Sensitization mechanisms of 1 µm luminescence in Tb3+–Yb3+ co‐doped borate glasses

Abstract

AbstractTb3+–Yb3+ co‐doped borate glasses were prepared and the ultraviolet/visible sensitization of infrared luminescence of Yb3+ has been evaluated by the photoluminescence (PL), the PL excitation (PLE) spectra, and the lifetime measurement. The Tb3+: 5D4–7FJ luminescence in visible range and the Yb3+: 2F5/2–2F7/2 luminescence at 1000 nm were observed upon the excitation of Tb3+: 4f levels by 378 and 488 nm. On the basis of the difference in behavior of the Yb3+ concentration dependence of the integrated PL intensity and lifetimes of the Yb3+:2F7/2 level by UV and blue excitations, the energy transfer (ET) paths by the UV, and blue excitation are different. The intervalence charge transfer (IVCT) band between the Tb3+–Yb3+ pair were observed in the PLE spectra monitoring the Yb3+ emission. We conclude that the ET is caused through the IVCT state by the UV excitation and the ET upon the 5D4 level excitation of Tb3+ by 488 nm is caused by phonon assisted ET or cooperative downconversion.