Around 2 μm fluorescence and energy transfer in Tm 3+ /Ho 3+ co-doped tellurite glass

Abstract In this work, the near-infrared photoluminescence properties in Tm 3 + /Ho 3 + co-doped tellurite glass was investigated. The tellurite glass with composition TeO 2 -ZnO-Na 2 O-La 2 O 3 was synthesized using conventional melt-quenching technique and characterized by UV/Vis/NIR absorption and near-infrared emission spectroscopies, fluorescence decay measurement and differential scanning calorimeter (DSC) analysis. Under the excitation of 808 nm laser diode (LD), a broadband 2.0 μm band luminescence ranging from 1600 to 2200 nm with a full width at half maximum (FWHM) of 362 nm was observed, which was contributed by 1.85 μm fluorescence from Tm 3 + : 3 F 4  →  3 H 6 and 2.05 μm fluorescence from Ho 3 + : 5 I 7  →  5 I 8 . The fluorescence emission of Ho 3 + was originated from the energy transfer from Tm 3 + to Ho 3 + ions, and the energy transfer mechanism was elucidated by analyzing fluorescence decay behavior of Tm 3 + and quantitative calculation of phonon contribution joined in the energy transfer process. Meanwhile, based on the absorption spectrum, some important spectroscopic parameters such as Judd-Ofelt intensity parameter, spontaneous radiative transition probability, fluorescence branching ratio, absorption and emission cross-sections, and gain coefficient spectrum were calculated to reveal the spectroscopic properties of doped tellurite glass. Furthermore, from the DSC curve it can be derived that the investigated glass possesses a good thermal stability with Δ T (=  T x  −  T g ) larger than 152 °C. These results indicate that Tm 3 + /Ho 3 + co-doped tellurite glass could be a promising gain medium applied for  2.0 μm near-infrared band broad fiber amplifiers and tunable fiber lasers.