Three-arm windmill plasmonic nanoantenna: polarization and symmetry-dependent optical characteristics

A robust windmill plasmonic nanoantenna is proposed by constructing of three gold ellipsoidal arms separated with a round nanogap. By using the Finite Element Method (FEM), the extinction spectra and the electric field distributions of the three-arm windmill plasmonic nanoantenna are numerically investigated in detail for understanding the polarization and symmetry-dependent optical characteristics of plasmonic nanoantenna. The simulation results show that the extinction characteristics of the windmill plasmonic nanoantenna are insensitive to the polarization of incident light, while their significantly enhanced local electric field can be efficiently excited and confined within the feed gap of windmill plasmonic nanoantenna by irradiating of light with an arbitrary polarized direction. Moreover, it is found that, multipole resonance is achieved by changing of the structure symmetry of three-arm windmill plasmonic nanoantenna. It is a beneficial reference for developing of the plasmonic nanoantenna with unique polarization characteristics in practical photonic applications.