Broadband achromatic metalens and meta-deflector based on integrated metasurface

Metasurfaces have attracted much attention due to their great ability to manipulate the electromagnetic field over an ultra-compact profile, which facilities the realization of the next generation diffractive optical elements. However, the broadband performance of the metasurface-based optical devices is still subject to the chromatic aberration. Although the broadband achromatic metalenses have recently been studied, the diameters and numerical apertures of the metalens are still limited by the requirement of large phase compensation. Such large phase dispersion is usually realized by sophisticated nanostructures of extremely high aspect ratios that are not easy to fabricate. Here we propose a new kind of metalens by integrating the dielectric pillars with a multi-level phase plate, and achromatic focusing and imaging can be achieved in the wavelength range from 1100 to 1500 nm. In addition, a broadband achromatic meta-deflector is also proposed, which could refract broadband incident light with the same refractive angle. Our integrated metasurface can provide large phase compensation while alleviating the aspect ratios of the composing nanopillars, and shows potential applications in designing arbitrary metadevices with dispersion engineering properties.