Multifunctional resonant wavefront-shaping meta-optics based on multilayer and multi-perturbation nonlocal metasurfaces

摘要

Photonic devices rarely provide both elaborate spatial control and sharp spectral control over an incoming wavefront.In optical metasurfaces,for example,the localized modes of individual meta-units govern the wavefront shape over a broad bandwidth,while nonlocal lattice modes extended over many unit cells support high quality-factor resonances.Here,we experimentally demonstrate nonlocal dielectric metasurfaces in the near-infrared that offer both spatial and spectral control of light,realizing metalenses focusing light exclusively over a narrowband resonance while leaving off-resonant frequencies unaffected.Our devices attain this functionality by supporting a quasi-bound state in the continuum encoded with a spatially varying geometric phase.We leverage this capability to experimentally realize a versatile platform for multispectral wavefront shaping where a stack of metasurfaces,each supporting multiple independently controlled quasi-bound states in the continuum,molds the optical wavefront distinctively at multiple wavelengths and yet stay transparent over the rest of the spectrum.Such a platform is scalable to the visible for applications in augmented reality and transparent displays.