Broadband NIR radiative transitions in Er3+/Tm3+co-doping tellurite glass material

The radiative property of Er3+/Tm3+ co-doping tellurite glass containing metallic silver nanoparticles (Ag NPs) in near-infrared (NIR) band region was studied under the 808 nm pumping. The tellurite glass was prepared by applying melt-quenching and heat-treated technique, and characterized by measuring differential scanning calorimeter (DSC) curve, transmission electron microscopy (TEM) image, absorption spectrum and fluorescence spectrum. Under the optimized combination of Er3+ and Tm3+ ions, a flat and wide NIR band fluorescence in spectral range of 1350 to 1650 nm with full width at half maximum (FWHM) of 161 nm, originating from Er3+:4I13/2 -> 4I15/2 radiative transition (1.53 mu m) and Tm3+:3H4 -> 3F4 radiative transition (1.47 mu m), was observed in the studied tellurite glass. The fluorescence intensity was increased by about 91% when the Ag NPs with size of -17.4 nm was embedded into the doping glass. A similar wide optical amplification spectrum was also observed through the theoretical simulation of stimulated radiative transition of tellurite glass fiber co-doped with Er3+/ Tm3+ ions, indicating the potential of Er3+/Tm3+ co-doping tellurite glass applied for broadband fiber amplifiers and tunable lasers. Additionally, the DSC curve revealed the excellent thermal stability of glass host with transition temperature of 381 degrees C and the difference between crystallization onset temperature and transition temperature of 141 degrees C. Some important spectral parameters like radiative transition probability and fluorescence branching ratio among different levels were determined according to Judd-Ofelt theory to better understand the observed broadband and flat NIR luminescence phenomenon.