Interaction between plasmonic nanoparticles revisited with transformation optics.

The interaction between plasmonic nanoparticles is investigated by means of transformation optics. The optical response of a dimer can be decomposed as a sum of modes whose resonances redshift when the nanoparticles approach each other. The extinction and scattering cross sections as well as the field enhancement induced by the dimer are derived analytically taking into account radiation damping. Interestingly, some invisibility dips occur in the scattering spectrum and originate from a destructive interference between each surface plasmon mode.