Subwavelength asymmetric Au–VO₂ nanodisk dimer for switchable directional scattering

We propose an asymmetric Au–VO₂ nanodisk dimer for realizing a switchable directional scattering. Specifically, the directional scattering can be triggered on/off through controlling the phase transition of the VO₂ 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 VO₂ nanodisk. This tunable directional scattering is further explained with an interference model where the Au and VO₂ nanodisks are treated as two weakly interacting electric dipoles. The phase transition controlled scattering patterns of asymmetric Au–VO₂ nanodisk dimer are then well interpreted from the phase difference between these two dipoles. (special topic)