Single-Element Diffraction-Limited Fisheye Metalens

TLDR

Wide field‑of‑view optical functionality is essential for advanced imaging and projection, yet it is usually achieved with complex assemblies of multiple elements. The authors aim to introduce a single‑layer metalens that delivers diffraction‑limited focusing and imaging over an almost 180° angular field of view. The metalens is a monolithic, single‑layer metasurface on a flat substrate that corrects third‑order Seidel aberrations, provides a planar focal surface, and is fabricated with Huygens meta‑atoms at 5.2 µm, enabling diffraction‑limited performance across the entire field. Experimental results demonstrate aberration‑free focusing and imaging over the full 180° field of view.

Abstract

Wide field-of-view (FOV) optical functionality is crucial for implementation of advanced imaging and image projection devices. Conventionally, wide FOV operation is attained with complicated assembly of multiple optical elements known as "fisheye lenses". Here we present a novel metalens design capable of performing diffraction-limited focusing and imaging over an unprecedented near 180° angular FOV. The lens is monolithically integrated on a one-piece flat substrate and involves only a single layer of metasurface that corrects third-order Seidel aberrations including coma, astigmatism, and field curvature. The metalens further features a planar focal surface, which enables considerably simplified system architectures for applications in imaging and projection. We fabricated the metalens using Huygens meta-atoms operating at 5.2 μm wavelength and experimentally demonstrated aberration-free focusing and imaging over the entire FOV. The design concept is generic and can be readily adapted to different meta-atom geometries and wavelength ranges to meet diverse application demands.