Spatially Variable Period Modulation Enables High-Efficiency Large-Field-of-View Metalens

Wide-field imaging is important for advanced optical systems, whereas conventional multielement refractive optics remain constrained by bulky form factors and large system weight. Metalenses provide a compact platform for wavefront manipulation, but their application to wide-angle focusing and imaging is limited by the pronounced efficiency degradation that occurs at large incident angles. Here, we propose a spatially variable period modulation strategy, in which the lattice period of the meta-atoms is locally tailored to accommodate the angle-dependent focusing requirement over a wide field of view. A rapid determination method based on a precomputed simulation database is further developed to reduce the computational cost of structural optimization. Experimentally, the fabricated planar single-layer metalens enables imaging over a 100° full field of view and maintains a focusing efficiency of 63% at an incident angle of 50°, while preserving compact focal spots and resolvable image features across the entire angular range. This work provides an effective route toward high-performance wide-field metalenses and offers a general framework for the design of angle-robust metasurface devices.