Anomalous optical response of metal–molecule coupled system

We theoretically investigate the optical response of a coupled system composed of a molecular dimer and metal structures forming a nanogap. The metal structures serve as a light harvesting antenna; a localized light field is strongly enhanced by the plasmon resonance at the nanogap, and the molecular dimer is strongly coupled with the antenna via this enhanced field. Through numerical calculations, we find that photon energies received by the metal antenna are concentrated into the molecules without being absorbed by the metal structures under particular resonance conditions. This metal-transparency effect can be understood by considering the interference between the eigenmodes of the metal–molecule coupled system.

► We study an interaction between the metallic antenna and molecules via localized plasmons.
► Their self-consistent interaction causes peculiar energy concentration into the molecules.
► Photon energy is strongly concentrated into the molecules via the antenna at particular conditions.
► We consider the coupled oscillators model to explain the above energy concentration.
► The interference between the eigenmodes of the coupled oscillators well explains this phenomenon.