Broadband mid-infrared emission in Dy3+/Er3+ co-doped tellurite glass

Highlights: • Dy³⁺/Er³⁺ co-doped tellurite glass was prepared by melt-quenching method. • An ultra-broadband 2550–3200 nm fluorescence emission with FWHM 358 nm was obtained. • Structural, thermal, spectroscopic properties and luminescent mechanism were investigated. • Dy³⁺/Er³⁺ co-doped tellurite glass is promising for MIR broadband tunable lasers. Broadband mid-infrared luminescence in Dy³⁺/Er³⁺ co-doped tellurite glasses was reported in this work. The doped tellurite glasses were prepared using conventional melt-quenching technique, and their structural property and thermal stability were analyzed by the X-ray diffraction (XRD) pattern, Raman spectrum and differential scanning calorimeter (DSC) curve. Judd-Ofelt theory was applied to the absorption spectra to evaluate the spectroscopic properties like radiative transition probability, branching ratio and radiative lifetime of Dy³⁺ and Er³⁺ ions. The photoluminescence measured under excitation of 808 nm laser diode (LD) displayed an ultra-broadband mid-infrared band emission with full width at half maximum (FWHM) of ~358 nm in tellurite glass with appropriate amount of Dy³⁺-Er³⁺ combination. This broadband mid-infrared band emission located in the range of 2550–3200 nm and originated from the spectral overlapping of 2.85 μm band emission of Dy³⁺:⁶H_13/2 → ⁶H_15/2 transition and 2.7 μm band one of Er³⁺:⁴I_11/2 → ⁴I_13/2 transition. Furthermore, the time resolved fluorescence decay behavior demonstrated the existence of energy transfer between Dy³⁺ and Er³⁺ ions which is responsible for the broadband luminescence, and the energy transfer efficiency was estimated. The present results indicate that tellurite glass co-doped with Dy³⁺-Er³⁺ ions is promising for applications in mid-infrared band luminescent sources and tunable lasers.