Surface plasmons, the coupling of photons to charges at metal interfaces, are widely used to improve efficiency of sensing, energy transfer, and catalysis. There has been much effort to optimize plasmonic systems and exploit their field enhancement property. However, the system structure, resonance frequencies, and field enhancement are all coupled, making characterization difficult. While Maxwell finite-domain time-difference (FDTD) simulations can handle ideal systems, measurement and characterization of realistic (imperfect) experimental systems is desired.

Recently, we developed a novel single molecule superresolution method to characterize plasmonic nanostructures. We use the field strength sensitivity of stochastic blinking in quantum dots (QDs) as an indirect measurement of the local field strength, allowing measurement of the localized plasmonic near-field with a far-field reporter. Using traditional confocal excitation with a wide field capture EMCCD camera, in conjunction with Maxwell FDTD simulations, metallic nanostructures were mapped out with high spatial and local field intensity precision. Our approach offers advantages such as low-cost, high-throughput, and superresolved mapping of localized plasmonic fields.