Comparative Investigation of Optical Properties in Tm³⁺/Er³⁺/Yb³⁺ Co-Doped Oxyfluoride Tellurite and Germanate Glasses

Abstract

Tm 3 + /Er 3 + /Yb 3 + co-doped oxyfluoride tellurite and germanate glasses have been synthesized by conventional melting method. Intense up-conversion (UC) luminescence emissions were simultaneously observed under 980 nm excitation at room temperature in two glasses. The possible UC mechanisms are discussed and estimated. However, in the studied Tm 3 + /Er 3 + /Yb 3 + co-doped oxyfluoride glasses, tellurite glass showed weaker UC emissions than germanate glass, which is inconsistent with the prediction from the difference of maximum phonon energy between oxyfluoride tellurite and germanate glasses. Absorption spectrum and Raman spectroscopy were employed to investigate the origin of the difference in UC luminescence in two glasses. Our results confirm that, besides the maximum phonon energy, the phonon density of host glasses is another important factor in determining the UC efficiency.