Dielectric metasurfaces for beam bending and near-unity numerical aperture lenses

In this work, we propose a novel approach to efficient high-angle light beam bending and demonstrate it using TiO
₂
and Si metasurfaces operating in the visible and near IR spectral ranges. The proposed approach allows large angle bending, with up to 82° experimentally demonstrated. Based on this concept we designed a lens with near-unity numerical aperture (NA~0.99), exceeding all previously reported values.