Local wavefront manipulation with high quality factor metasurfaces

We report on an all-dielectric higher-order Huygens metasurface for local wavefront manipulation in two dimensions with high quality factor at near-infrared wavelengths. Our metasurface consists of a subwavelength-spaced array of high index nanopillars exhibiting spectrally overlapped electric dipole and electric octupole modes. The local control over these modes enables modulating the phase of the transmitted light with only a ±1% change in the nanopillar dimensions. Based on this, we experimentally realize beam deflection along two perpendicular dimensions with quality factors ranging between Q = 300–1472, and radial metalenses with quality factors up to Q = 916. The local control over the wavefront allows operation with finite illumination apertures and angled illumination. Our results contrast with other high-quality-factor optical metasurfaces which rely on guided mode resonances or bound states in the continuum, limiting their application to one-dimensional wavefront shaping or geometric phase tuning, respectively.