Localized field control at the nano-scale

We investigate the wavelength dependence of localized plasmonic field distributions in a gold nanodimer structure under total internal reflection condition. Although a gold dimer structure is well known to induce strong localized mode at a nanogap, we find that the higher-order plasmonic modes are excited by the oblique light incidence and their interference effect enables us to observe the modification of localized filed distributions at the nano-scale even in a simple gold nanodimer structure depending on the detection wavelength. This change in the plasmonic field distribution would provide important knowledge for their potential applications such as plasmonic trapping, spectroscopy, and sensing.