Enhanced 1.80 μm fluorescence in Er3+/Yb3+/Tm3+ tri-doped tellurite glass for fiber lasers

Abstract Improving the lasing emission property of rare-earth doped vitreous material is a research topic. In this paper, Er 3+ /Yb 3+ /Tm 3+ tri-doped tellurite glasses with and without WO 3 component were synthesized using melt-quenching technique and the effect of WO 3 addition on the 1.80 μm band fluorescence of Tm 3+ was investigated. The obtained samples were characterized by X-ray diffraction (XRD) pattern, differential scanning calorimeter (DSC) curve, Raman spectrum, UV/Vis/NIR absorption spectrum, near-infrared emission spectrum and fluorescence decay curve. The XRD pattern confirmed amorphous structural nature of synthesized tellurite glass, the DSC curve revealed good thermal stability with Δ T >100 °C and the Raman spectrum displayed a stretching vibration band around 920 cm −1 for glass host with WO 3 . Under the excitation of 980 nm laser diode (LD), the intense 1.80 μm band fluorescence of Tm 3+ originated from the 3 F 4 → 3 H 6 transition was observed in the Er 3+ /Yb 3+ /Tm 3+ tri-doped tellurite glass and the intensity increases further with the addition of a certain amount of WO 3 , which is attributed to the enhanced energy transfers from Yb 3+ (Er 3+ ) to Tm 3+ ions due to the increased phonon energy of glass host. The energy transfer mechanism between them was elucidated by analyzing fluorescence decay behavior of Tm 3+ and quantitatively calculating energy transfer coefficient as well as phonon contribution ratio. Meanwhile, based on the absorption spectrum, some important spectroscopic parameters such as Judd-Ofelt parameter, spontaneous radiative transition probability, fluorescence branching ratio, absorption and emission cross-sections, and gain coefficient spectrum were calculated to reveal spectroscopic properties of doped Tm 3+ ions. The obtained results indicate that Er 3+ /Yb 3+ /Tm 3+ tri-doped tellurite glass with an appropriate amount of WO 3 is a promising gain medium applied for the 1.80 μm band solid-state lasers.