Silver Nanoparticles Enhanced Upconversion Luminescence in Er³⁺/Yb³⁺ Codoped Bismuth-Germanate Glasses

Abstract

Surface plasmon resonance (SPR) of noble metal nanoparticles (NPs) fostered a new area of nanophotonics, especially in the selective photon absorption and scattering. The precipitation of Ag NPs in glass would enhance the emission efficiency. Here, we studied the effects of annealing temperature (resulted in the increased Ag NPs’ concentration) or AgCl concentration on the luminescence properties of Er³⁺/Yb³⁺ codoped bismuth-germanate glasses which were synthesized by a single-step melting–quenching technique. The SPR peak of Ag NPs appears around 600 nm, and the size of precipitated Ag NPs (spherical, hexagonal) ranges from 5 to 15 nm. With the precipitation of the Ag NPs, more intense green (527 nm, 548 nm) and red (661 nm) upconversion (UC) emission bands are observed up to 7.7, 10.1, and 6.5 folds in the glass containing 1 wt % AgCl annealed at 480 °C for 24 h, respectively. The Ag NPs embedded glasses showed significantly local field change that allowed for more bright UC emission by SPR.