Fluorescence coupling to plasmonic nanoparticles

The combination of single photon emitters (quantum dots) and tailored metal nanoparticles with defined size and shape allows a detailed study of the interaction between light and matter. The enhanced optical near-field of the nanoparticles can strongly influence the absorption and emission of nearby fluorescent quantum dots. We show that a controlled spatial arrangement enables the analysis and understanding of polarization dependent coupling between a metal nanoparticle and few or single fluorescent quantum dots. Modifications in the fluorescence spectrum and lifetime are analyzed and compare well with simulations. The reduction of the fluorescence lifetime in such systems is usually in the order of 3-10. However, much larger reductions are to be expected if the quantum dots are positioned in a nanometric gap between two plasmonic nanoparticles, eventually leading to hot luminescence. We approach this regime experimentally and present first results from lithogaphically fabricated gold particle-pairs with controlled gap widths in the range of 1-20nm.