Electrically controlled nonlocal metasurfaces

Nonlocal metasurfaces extend the capabilities of flat optics by exploiting collective, spatially extended electromagnetic modes that enable momentum-dependent control of light within an ultrathin platform. When combined with electrical tunability, such metasurfaces move beyond static wavefront shaping toward dynamic, programmable manipulation of optical fields. In this Focus Article, we review recent advances in electrically controlled nonlocal metasurfaces, highlighting the physical mechanisms that underpin nonlocal responses, including coupled-resonator networks, guided-mode resonances, and surface lattice resonances. We discuss how electrical control based on carrier modulation, phase-change materials, and electro-optic effects enables dynamic tuning of phase, amplitude, and wavevector, and how resonant nonlocal architectures enhance otherwise weak modulation strengths. Finally, we examine emerging spatiotemporal nonlocal metasurfaces that combine collective momentum-dependent responses with ultrafast electrical modulation, enabling frequency-momentum conversion, adaptive wave-based signal processing, and nonreciprocal optical functionalities. Together, these developments point toward a new generation of reconfigurable, ultrathin photonic systems that compress complex optical operations into a single electrically programmable interface.