Structural, thermal and broadband NIR emission properties of Nd 3+ /Pr 3+ /Ag NPs co-doped tellurite glass

Nd3+/Pr3+ co-doped tellurite glasses containing metallic Ag NPs were synthesized by melt-quenching and heat-treating techniques. The amorphous structural nature, fundamental vibrational units and good thermal stability of the prepared tellurite glasses were confirmed by X-ray diffraction (XRD) pattern, Raman spectrum and differential scanning calorimeter (DSC) curve, respectively. The precipitated Ag NPs in a glass matrix with an average diameter ∼5 nm were revealed by transmission electron microscopy (TEM) image, and the radiative property of Nd3+ and Pr3+ ions was evaluated from the absorption spectrum by Judd-Ofelt theory. Under the excitation of 488 nm Xenon lamp, two broadband near-infrared emissions covering 800-1100 nm and 1250-1650 nm ranges were observed from the fluorescence spectrum. The former originated from the transitions of Pr3+:3P1,0→1G4, Pr3+:1D2→3F4,3, Nd3+:4F3/2→4I11/2 and Nd3+:4F3/2→4I9/2, while the latter was contributed by the Pr3+:1G4→3H5, Pr3+:1D2→1G4, Pr3+:3F3→3H4 and Nd3+:4F3/2→4I13/2 transitions. With the introduction of Ag NPs, the emission intensity of two broadband near-infrared emissions was further enhanced, in which the peak emission intensity of 1250-1650 nm band was increased by about 56% and the FWHM is up to 250 nm. The obtained results indicate that Nd3+/Pr3+/Ag NPs co-doped tellurite glass has great potential in realizing ultra-broadband near-infrared emission covering O-, E- and S-bands simultaneously.