Unidirectional scattering and displacement sensing in V-shape nanoantennas

Nanoscale manipulation of optical fields, particularly for achieving unidirectional scattering, is crucial for the advancement of photonic technologies. Traditional approaches to unidirectional scattering involving vector beams and metallic structures have largely relied on multimers and the interactions between electric dipoles. Here, we introduce a theoretically novel method that leverages a single Au V-shaped antenna and azimuthally polarized beam to achieve transverse unidirectional scattering predominantly governed by electric dipole-quadrupole interactions. This unidirectional scattering phenomenon is preserved despite positional variations of the V-antenna within the light field, with scattering intensity distributions being highly position-dependent. Building on these insights, we developed a composite system of two oppositely oriented V-antennas, enabling transverse displacement sensing over a range of 250 nm (∼0.38λ) in the visible spectrum. This work not only enhances optical manipulation capabilities in metallic nanoantennas but also introduces innovative strategies for transverse displacement sensing with a substantial measurement range in the visible spectrum, underscoring significant potential for diverse applications.