Abstract
Among various flat optical devices, metasurfaces have presented their great ability in efficient manipulation of light fields and have been proposed for variety of devices with specific functionalities. However, due to the high phase dispersion of their building blocks, metasurfaces significantly suffer from large chromatic aberration. Here we propose a design principle to realize achromatic metasurface devices which successfully eliminate the chromatic aberration over a continuous wavelength region from 1200 to 1680 nm for circularly-polarized incidences in a reflection scheme. For this proof-of-concept, we demonstrate broadband achromatic metalenses (with the efficiency on the order of ∼12%) which are capable of focusing light with arbitrary wavelength at the same focal plane. A broadband achromatic gradient metasurface is also implemented, which is able to deflect wide-band light by the same angle. Through this approach, various flat achromatic devices that were previously impossible can be realized, which will allow innovation in full-color detection and imaging.
Highlights
Among various flat optical devices, metasurfaces have presented their great ability in efficient manipulation of light fields and have been proposed for variety of devices with specific functionalities
To realize a broadband achromatic metalens (BAML), which is schematically shown in the right side of Fig. 1a, such phase retardation with a fixed focal length is exactly required in a wide range of wavelength
The BAML with very high numerical aperture (NA) can be realized with our design principle
Summary
Among various flat optical devices, metasurfaces have presented their great ability in efficient manipulation of light fields and have been proposed for variety of devices with specific functionalities. We propose a design principle to realize achromatic metasurface devices which successfully eliminate the chromatic aberration over a continuous wavelength region from 1200 to 1680 nm for circularly-polarized incidences in a reflection scheme For this proof-of-concept, we demonstrate broadband achromatic metalenses (with the efficiency on the order of ∼12%) which are capable of focusing light with arbitrary wavelength at the same focal plane. Recent works reported the dielectric metasurfaces for metalens with high numerical aperture (NA) and optical planar camera with monochromatic aberrations that are comparable with the commercial products, presenting their potential prospect in real applications[23, 24] These proposed metasurface devices still exhibit large chromatic aberration, which is mainly attributed to following fundamental properties: the resonant phase dispersion of the building blocks used in metasurfaces, the intrinsic dispersion in used materials, as well as the different phase accumulation through light propagation in free space with various wavelengths. The broadband achromatic metasurface devices based on our approach greatly innovate a complete class of designs in full-color light manipulation and imaging and push them forward to the practical applications
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