Broadband active tuning of unidirectional scattering from nanoantenna using combined radially and azimuthally polarized beams

Abstract

We propose an approach to actively tune the scattering pat-tern of a Mie-type spherical antenna. The scheme is basedon separate control over the induced electric dipole and in-duced magnetic dipole using two coherent focused beams ofradial polarization and azimuthal polarization, respectively.By carefully tuning the amplitude and phase relation of thetwo beams, a broadband unidirectional scattering can beachieved, even at the antenna’s resonant wavelength wherethe antenna scatters efficiently. By moving the focus of onebeam, a drastic switch of the unidirectional scattering canbe observed. Such a scheme enables the design of ultra-compact optical switches and directional couplers basedon nanoantennas.