Analysis of Asymmetric Dipoles Interacting in Heterogeneous Metal Nanorod Dimers

The localized electric field enhancement of Au-Ag nanorods dimer is theoretically investigated based on finite element method (FEM). An analytical mutual-interference model between asymmetric dipole-dimer has been built to describe the dipoles coupling with different resonance modes in heterogeneous dimer. Three prominent enhancement peaks could be observed from ultraviolet to visible spectrum, in which the ultraviolet resonance especially corresponds to a higher mode in both Ag and Au nanorods. The results reveal the strong coupling mechanism among different dipoles existing in the asymmetric dipole system, which could support the design of plasmonic nanodevices in larger resonance wavelength range.