The light-matter interactions between dyes and plasmonic nanoparticle antennas have attracted attention due to the resulting strong spectroscopic enhancements, and single-molecule investigations have measured modifications in the far-field emission patterns of plasmon-coupled fluorescent molecules. Here, we measure with single-molecule polarization-resolved microscopy that the emission polarization from a dye molecule is rotated upon coupling to an asymmetric nanoantenna and we determine that the emission polarization from the coupled system indicates the direction of the gold nanorod’s dominant local surface plasmon polariton mode. We measure how this polarization emission modification depends on the dye absorption and emission spectrum, and we determine that the most strongly coupled dye molecules show both the greatest fluorescence intensity enhancement and the most emission polarization modification. We interpret our results in the context of full-field electromagnetic simulations and we understand the dye/nanoparticle coupling with an analytical model. To our knowledge, this is the first study that deliberately tunes the fluorescence polarization of single molecules via nanoantenna coupling. This study increases our understanding of plasmon-coupled emission modifications and promises to improve high-sensitivity single-molecule fluorescence imaging and biosensing by increasing the tunability and control of plasmon-enhanced fluorescence.

Single-molecule emission polarization modification by plasmonic nanorods

2019 Fall National Meeting

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