Optical characterization of Tm3+ in a high barium-tellurite glass in absence and presence of Yb3+: Evidence of strong crystal-field effect and efficient Yb3+→Tm3+ energy transfer

Strong ~1.83 μm NIR-emission of the Tm3+ doped glass and its calculated high values of gain cross-section suggest that the glass is prospective for use as 1.75-1.90 μm tunable solid state laser-medium; while the observed intense 804 nm upconversion emission of the co-doped glass indicates that the material should be useful as a bio-marker.