The lightning-rod mode in a core shell nanocylinder dimer

Optical properties of a dielectric-core gold–shell nanocylinder pair are investigated by two-dimensional finite difference time domain method. The results show that the plasmonic interaction between the two dielectric-core gold–shell nanocylinders could contain an additional plasmon mode. This additional plasmon mode is resulted from the coupling of the electron at the outer surfaces of the two nanocylinders due to gold shell and gold/dielectric boundary that block electromagnetic wave. Depending on the permittivity of the dielectric core and shell thickness of the nanocylinders, we can decide the existence of this additional plasmon mode in the spectrum.