Anomalous Beam Deflection Enabled by Resonant Polarization States in Nonlocal Phase Gradient Metasurfaces

ABSTRACT Guided mode resonances with intriguing nonlocal responses have introduced new opportunities in metasurfaces by offering high spatial and spectral resolutions to the control of optical wavefronts. Especially, the in‐plane symmetry of the meta‐atom provides a degree of freedom to tailor the polarization states distribution of guided mode resonances in the momentum space, which can be utilized to control the geometric phase of incident light. However, although such a phase control method has already been applied to generate vortex light sources in the momentum space, it is still elusive to control the wavefront of light in real space. Herein, we present the experimental demonstration of the real‐space wavefront shaping by using resonant linear polarization states in nonlocal guided mode resonant metasurfaces. By reducing the symmetry of the metasurfaces to three‐fold rotational (C3) symmetry, we can realize resonant linear polarization states at the Γ point. Such linear polarization states result in a high‐order geometric phase relation, enabling a full phase coverage of 2π for the meta‐atom with a rotation of only π/3. Consequently, the resonant nonlocal phase gradient metasurfaces can function as polarization‐selective beam deflectors, enabling chirality‐dependent beam deflection with controllable angles.