RGB Achromatic Metalens Doublet for Digital Imaging br

Chromatic aberration is a major challenge faced bymetalenses. Current methods to achieve broadband achromaticoperation in metalenses usually suffer from limited size, numericalaperture, and working bandwidth due to thefinite group delay ofmeta-atoms, thus restricting the range of practical applications.Multiwavelength achromatic metalenses can overcome thoselimitations, making it possible to realize larger numerical aperture(NA) and sizes simultaneously. However, they usually requirethree layers, which increases their fabrication complexity, and haveonly been demonstrated in small sizes, with low numerical apertureand modest efficiencies. Here, we demonstrate a 1 mm diameterred-green-blue achromatic metalens doublet with a designed NAof 0.8 and successfully apply the metalens in a digital imagingsystem. This work shows the potential of the doublet metasurfaces, extending their applications to digital imaging systems such asdigital projectors, virtual reality glasses, high resolution microscopies, etc