Interaction between Au nanoparticles and Er3+ ions in a TiO2 matrix: Up-conversion of infrared light

Up-conversion luminescence of rare-earth ion-doped materials has been demonstrated in the TiO2:Er3+ system when Au nanoparticles are in close vicinity to the Er3+ ions. From the combination of photoluminescence and photospectro-metry studies it is concluded that the up-conversion is enhanced as a result of the excitation of localized surface plamon resonances in the Au nanoparticles. Indications are found that the dominant source of the enhancement is a resonant local-field enhancement of the excitation process.