The 1.85 mm spectroscopic properties of Er3+/Tm3+ co-doped tellurite glasses containing silver nanoparticles

The Er3+/Tm3+ co-doped tellurite glasses with and without silver nanoparticles (Ag NPs) have been synthesized by the conventional melt-quenching technique and characterized by the UV/Vis/NIR absorption spectra, 1.85 mu m band fluorescence emission spectra, differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) curves and transmission electron microscopy (TEM) images to investigate the effects of Ag NPs on the 1.85 mu m band spectroscopic properties of Tm3+ ions, thermal stability and structural nature of glass hosts. The TEM image reveals the presence of Ag NPs with average diameter of similar to 14 nm in the prepared Er3+/Tm3+ co-doped tellurite glasses, and the presence of Ag NPs significantly enhance the 1.85 mm band fluorescence emission of Tm-3+ ions under the excitation of 808 nm LD, which is mainly attributed to the intensified local electric field induced by Ag NPs scattered around the doped rare-earth ions, together with the energy transfer between Er3+ and Tm3+ ions. The energy transfer mechanisms between Er3+ and Tm3+ ions were further investigated by calculating energy transfer microparameters and phonon contribution ratios. Meanwhile, the Judd-Ofelt intensity parameters Omega(t)(t - 2,4,6), spontaneous radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of relevant excited levels of Tm3+ ions were calculated based on the Judd-Ofelt theory to reveal the improved effects of Ag NPs on the 1.85 mu m band spectroscopic properties. An improvement by about 75% of fluorescence intensity is found in the studied Er3+/Tm3+ co-doped tellurite glass containing 1.0 mol% amount of Ag NPs, and the thermal stability of glass host increases slightly with the Ag NPs while the glass structure maintains the amorphous nature. The above results indicate that the prepared Er3+/Tm3+ co-doped tellurite glass with an appropriate amount of Ag NPs is a promising host material applied for 1.85 mu m band solid-state lasers and amplifiers. (C) 2016 Elsevier B.V. All rights reserved.