Sensitizing effect of Ho3+ on the Er3+: 2.7 μm-emission in fluoride glass

The fluorescence properties of 2.7 μm emission and energy transfer mechanism of Ho3+/Er3+ co-doped fluoride glass (ZBYA) have been investigated in the present paper. Ho3+ strengthens the Er3+: 2.7 μm emission in the ZBYA glasses due to the energy transfer from Er3+ to Ho3+, while the 1.5 μm emission decreases dramatically. The optimized concentration ratio of Er3+ to Ho3+ is found to be 1:1 in our glass system. The absorption and emission spectra are tested and the sample possesses large emission cross section (16.5 × 10−21 cm2) around 2.7 μm along with larger radiative transition probability (25.11 S−1) on the basis of Judd-Ofelt and Fuchtbauer-Ladenburg theories. Additionally, the energy transfer microparameters are calculated using Förster-Dexter theory and the result shows the energy transfer coefficient of Er3+:4I13/2 → Ho3+:5I7 is 24 times larger than that of Er3+:4I11/2 → Ho3+:5I6. Our results show that Er3+: 2.7 μm emission can be sensitized by Ho3+ efficiently, and this Er3+/Ho3+-codoped fluoride glasses might have potential application in mid-infrared lasers.