Engineering Angular Dispersion via Hybrid Local-Nonlocal Metasurfaces

Conventional dielectric metasurfaces typically exhibit broadband spectral and angular responses, as their individual elements inherently possess broadband characteristics with weak near-field coupling between adjacent resonators. In contrast, nonlocal metasurfaces leverage collective electromagnetic interactions to achieve narrow spectral and angular selectivity, but often introduce polarization dependence arising from structural asymmetry. Here, we demonstrate a uniform and polarization-insensitive metasurface that overcomes this typical trade-off by deliberately combining local and nonlocal optical responses within a single platform. The proposed silicon nanopillar metasurface exhibits high transmission with pronounced angular discrimination through resonator engineering and periodicity-driven control of collective modes, maintaining over 80% transmission within a ± 15° incidence cone while exhibiting strong attenuation outside this range. The engineered periodicity enables control over lattice-mediated collective modes and substrate-guided diffraction channels, with the latter becoming trapped within the substrate and thereby suppressing transmission into free space at larger incidence angles. Numerical simulations and experimental measurements show good agreement and validate the underlying design strategy. These findings establish a compact platform for angular-selective optical components with potential applications in imaging, sensing, and LiDAR systems.