Enhanced optical functionalities in silica by doping with Au-based nanostructures

Abstract

The sensitization mechanism of Er3+ ions by sub-nanometric AuN aggregates formed in silica by sequential ion implantation has been investigated by room temperature photoluminescence characterizations. Er–Au co-implanted samples with different Au and Er relative concentrations have been studied. The results allowed to point out a correlation between the luminescence properties of the molecule-like AuN nanoclusters and the Er sensitization effect and to definitely prove the short-range nature of the energy-transfer process

Au–Ag nanoalloy molecule-like clusters for enhanced quantum efficiency emission of Er3+ions in silica

“…It is important to note that this behavior is significantly different from what has been revealed for molecule-like Au nanoclusters in Er-doped silica samples. With regard to the Er-Au co-implanted samples, in fact, it was recently demonstrated by our group that the nanocluster-related luminescence band at 980 nm (which is resonant with the 4 I 15/2 -4 I 11/2 Er 3+ absorption transition) participates in the energy-transfer to Er 3+ ions through a nonradiative, short-range process, 20,25 and a strict anti-correlation is observed between the PL emission intensity at 980 nm and the Er 3+ luminescence at 1540 nm: 25,43 in the presence of Er, the energy transfer from the molecule-like Au nanoclusters to Er 3+ ions (and the subsequent Er 3+ luminescence emission) is favored with respect to the radiative de-excitation of the Au nanoclusters at 980 nm, which occurs instead when Er is not present. Conversely, for the Er-AuAg samples investigated in the present work the presence of Er does not affect significantly the radiative properties of the Au-Ag alloy nanoclusters.…”

Emission Efficiency Enhancement of Er3+ Ions in Silica by Near‐Field Coupling With Plasmonic and Pre‐Plasmonic Nanostructures

“…Therefore the experimental findings suggest that the enhancement of the Er 3+ emission at 1.54 μm is due to the sensitization effect of Ag pre‐plasmonic clusters with a mechanism similar to the one recently demonstrated for Au and AuAg sub‐nanometric clusters . When noble metal nanoclusters are in close proximity ( nm) to Er ions, they are able to absorb the incident light through broad‐band interband transitions (with an absorption cross‐section much higher than the Er 3+ one) and efficiently transfer the energy to the nearby Er ions via a short‐range non‐radiative mechanism …”

Interstitial oxygen related defects and nanovoids in Au implanteda-SiO2glass depth profiled by positron annihilation spectroscopy

“…These phenomena can be related to a transition regime between bulk and molecule-like structure properties of the ultra small clusters of which electronic configuration supports discrete electronic levels with an energy gap between the highest occupied and the lowest unoccupied molecular orbital (HOMO-LUMO gap) [18]. Room temperature photoluminescence (PL) emission of small Au nanoclusters of 5-10 atoms in size was reported in the 600-1500 nm wavelength range [19] and it was suggested that, in co-implanted Au and Er silica, part of the energy adsorbed by the Au nano-clusters is transferred to Er increasing the excitation cross section of the rare earth [20]. In these systems the presence of defects introduced by implantation near or at the surface of the nano-clusters and which are not completely recovered after the annealing treatments, can act as detrimental non-radiative recombination channels for the PL.…”