We propose an asymmetric Au-VO 2 nanodisk dimer for realizing a switchable directional scattering. Specifically, the directional scattering can be triggered on/off through controlling the phase transition of the VO 2 nanodisk from metallic to semiconductor state. More strikingly, an obvious directional scattering with the directivity of ∼ 40 dB is achieved under the metallic state of VO 2 nanodisk. This tunable directional scattering is further explained with an interference model where the Au and VO 2 nanodisks are treated as two weakly interacting electric dipoles. The phase transition controlled scattering patterns of asymmetric Au-VO 2 nanodisk dimer are then well interpreted from the phase difference between these two dipoles.

Unidirectional scattering of various plasmonic nanoantennas has been extensively studied, giving birth to applications such as optical sensors, solar cells, spectroscopy and light-emitting devices. The directional scattering of magnetic nanoantennas remains unexplored, though obvious benefits of artificial magnetism applications including metamaterials, cloaking and nonlinear optical resonance. In this work, we numerically investigate the far-field scattering properties of the Si ring-Au split ring nanoantenna (Si R-Au SRN) excited by a tightly focused azimuthally polarized beam (APB) with the finite-difference time-domain (FDTD) method. The results show that the magnetic resonant peak with different width can be deterministically excited in Si ring and Au split ring by tightly focused APB. Due to the plasmon hybridization effect, the two magnetic resonant modes form antibonding mode and bonding mode in the Si R-Au SRN. At the wavelength of λ=1064 nm, the destructive interference between the antibonding and bonding modes of nanostructure results in unidirectional far-field scattering in the transverse plane, which affect dramatically by changes of geometrical parameters. Furthermore, the directional scattering of a dipole source is realized by the designed nanostructure, and its scattering directionality is superior to that excited with APB. Our work provides a flexible way to control the far-field scattering of nano-photon structures. We envision that it could provide an avenue towards the nano-light sources and optical sensors.