Abstract
—Nonlocal metasurfaces, engineered structures in which spatially extended guided or diffractive modes mediate long-range coupling among sub-wavelength elements, are emerging as a promising platform for electromagnetic (EM) wave manipulation in future wireless networks. By transcending the pointwise response of conventional local metasurfaces, nonlocal designs unlock simultaneous and independent control of wave-front amplitude, phase, polarisation, and angular momentum across the entire aperture, capabilities that are difficult to realise simultaneously using conventional local architectures. This article provides a comprehensive overview of the two principal classes of nonlocal metasurfaces, nondiffractive and diffractive, and examines their impact on four pivotal application domains: high-performance leaky-wave metasurface antennas for spatially multiplexed 6G front-ends, analogue optical computing for real-time signal processing at the speed of light, advanced imaging and sensing paradigms including compressive and event-based modalities, and ultra-compact device architectures enabled by spaceplate-based spatial compression. We further identify critical future research directions, including selective angular and frequency filtering for intelligent channel engineering, reconfigurable nonlocal designs compatible with FPGA/ASIC control, spatio-temporal modulation for nonreciprocal operation and physical-layer security, and deep-learning-augmented design frameworks for electrically large apertures. Taken together, these advances position nonlocal metasurfaces as a promising and rapidly maturing platform for the next generation of high-capacity, low-latency, and hardware-efficient wireless systems, while their practical deployment will depend on addressing significant physical, fabrication, and integration challenges that we also discuss.