Nanoscopy through a plasmonic nano-lens

Plasmonics now delivers sensors capable of detecting single-molecules. The emission enhancements and nanometre-scale optical confinement achieved by these metallic nanostructures vastly increase spectroscopic sensitivity, enabling real-time tracking. However, the interaction of light with such nanostructures typically loses all information about the spatial location of molecules within a plasmonic hot spot. Here we show that ultrathin plasmonic nanogaps support complete mode sets which strongly influence the far-field emission patterns of embedded emitters, and allow the reconstruction of dipole positions with 1 nm precision. Emitters in different locations radiate spots, rings and askew halo images, arising from interference of two radiating antenna modes differently coupling light out of the nanogap, highlighting the imaging potential of these plasmonic ‘crystal balls’. Emitters at the centre are now found to live indefinitely, because they radiate so rapidly.