2–3 μm emission and fluorescent decaying behavior in Ho3+-doped tellurium germanate glass

Abstract In this work, we report the 2.05 μm emission and ∼3 μm broadband spectra of Ho2O3-doped 33GeO2–30TeO2–27PbO–10CaO (in mol%) glass under 640 nm laser excitation. Clear emission spectra due to the 5I7–5I8 transition and the 5I6–5I7 transition in Ho3+ are observed. The 2.05 μm emission intensity and the full width at half maximum (FWHM) of the ∼3 μm broadband depend on the Ho concentration. The peak stimulated emission cross-section of Ho3+ is 6.57 × 10−21 cm2 at 2.05 μm, as calculated by the McCumber theory. The emission spectra are recorded and the maximum emission intensity at 2.05 μm is obtained at a doping level of 0.5 mol% Ho2O3 in the glass. A broad and flat emission band from 2700 nm to 3050 nm is observed in 2 mol% Ho2O3-doped tellurium germanate glass. The lifetime of the 5I7 state decreases with the increase in Ho3+ concentration due to non-radiative relaxation processes. An energy transfer coefficient of 271.88 mol−1 s−1 is obtained.