Polarization Dependence of Plasmonic Nanotoroid Dimer Antenna

The surface Plasmon resonance of nanotoroid dimer antenna immersed in air is investigated. The method-of-moments surface integral equation is employed to compute the resonance wavelength and the enhanced electric field of the nanoantenna. The results show that the size of the gap causes redshift to the resonance wavelength of the dominant mode only when the incident polarization is parallel to the axis of the dimer. The dominant mode is a symmetric mode, and the higher order mode is a combination of symmetric and antisymmetric modes.