Structural and fluorescence properties of Ho3+/Yb3+ doped germanosilicate glasses tailored by Lu2O3

Structural and fluorescence properties of Ho3+/Yb3+ co-doped germanosilicate glasses have been modified by tailoring the composition using lanthanide additive Lu2O3. Raman spectra and X-ray Photoelectron spectra reveal that the addition of Lu2O3 can change the structure by increasing non-bridging oxygens (NBO) in this glasses. Meanwhile, an improved thermal stability (ΔT: from 110 to 187 °C) has also been obtained via Lu3+ 'lanthanide contraction'. Futhermore, the positive effect of changed glass structure gives excellent fluorescence properties by the decreasing cross relaxation process which are proved by the experimental upconversion, near-infrared and mid-infrared fluorescence spectra. Additionally, a double enhancement of a 2.0 μm emission has been achieved successfully in this silica-germanate glass with 7 mol% Lu3+ addition, which possesses a larger emission cross section (4.41 × 10−21 cm2) at 2022 nm. These results indicate that the optimized emission of Ho3+ for optical fiber laser can be achieved by tuning the glass structure using lanthanide additive Lu2O3.