2 μm mid-infrared optical spectra of Tm3+-doped germanium gallate glasses

Glasses with the composition of 65GeO212Ga2O3-10BaO-8Li2O-5La2O3(molar ratio) doped with 1.526 wt.%, 3.006 wt.%, 5.836 wt.%, 11.028 wt.%, and 15.678 wt.% Tm2O3, respectively, were fabricated by conventional melting method. According to the absorption spectra and the Judd-Ofelt theory, the J-O strength parameters (Ω2,Ω4, Ω6) were calculated, with which the radiative transition probabilities,branching ratios and radiative lifetimes were obtained. The infrared emission spectra (with 808 nm LD excitation) at～1.47 and～1.8 μm of various concentrations of Tm3+-doped glasses were studied. The emission intensity at～1.8 μm reached to the maximum when the Tm2O3-doping concentration was near to be～3.006 wt.% (1.0 mol.%), and then decreased as doping concentration increased further. The mechanism of the fluorescence intensity change was explained with the cross-relaxation effect and the concentration quenching effect of Tm3+. Meanwhile, according to McCumber theory, the absorption and emission cross-sections corresponding to the 3F4→3H6 transitions of Tm3+ at 1.8 μm was obtained. For Tm3+-doped germanate glasses, the maximum emission cross-section reached a value higher than that re-ported for fluorozircoaluminate glasses. It is expected to be a favorable candidate host for～2.0 μm mid-inflated laser because the glass shows favorable optical spectra.

2 μm mid-infrared optical spectra of Tm-doped germanium gallate glasses

Glasses with the composition of 65GeO₂-12Ga₂O₃-10BaO-8Li₂O-5La₂O₃ (molar ratio) doped with 1.526 wt.%, 3.006 wt.%, 5.836 wt.%, 11.028 wt.%, and 15.678 wt.% Tm₂O₃, respectively, were fabricated by conventional melting method. According to the absorption spectra and the Judd-Ofelt theory, the J-O strength parameters (Ω₂, Ω₄, Ω₆) were calculated, with which the radiative transition probabilities, branching ratios and radiative lifetimes were obtained. The infrared emission spectra (with 808 nm LD excitation) at 1.47 and 1.8 μm of various concentrations of Tm³⁺-doped glasses were studied. The emission intensity at 1.8 μm reached to the maximum when the Tm₂O₃-doping concentration was near to be 3.006 wt.% (1.0 mol.%), and then decreased as doping concentration increased further. The mechanism of the fluorescence intensity change was explained with the cross-relaxation effect and the concentration quenching effect of Tm³⁺. Meanwhile, according to McCumber theory, the absorption and emission cross-sections corresponding to the ³F₄→³H₆ transitions of Tm³⁺ at 1.8 μm was obtained. For Tm³⁺-doped germanate glasses, the maximum emission cross-section reached a value higher than that reported for fluorozircoaluminate glasses. It is expected to be a favorable candidate host for 2.0 μm mid-infrared laser because the glass shows favorable optical spectra.