Upconversion luminescence properties of Er3+-doped TeO2-PbF2 glass with and without Ag nanoparticles

Er3+-doped TeO2-PbF2 glasses with and without Ag nanoparticles (NPs) were prepared using a melt-quenching method. Ag precipitation was subsequently induced by heat treatment. The influence of Ag nanoparticles on the optical properties of Er3+-doped glasses was determined using optical absorption and photoluminescence spectroscopy. Upconversion (UC) emission properties were mainly dominated by the structural properties of the glass matrix. Ag+ doping and NP formation contributed to the enhancement of the total UC emission intensities. However, the green emission property of the glasses closely depended on the Ag NP size, and transition from quenching to enhancement occurred when the NP size of the Er3+-Ag co-doped glasses was increased. This size-dependent effect originated from the trade-off between the absorption and local field enhancement of Ag NPs with respect to the green emission of Er3+ ions.