Flat optics based on metasurfaces: Molding wavefronts with optical antenna arrays

Summary form only given. Metasurfaces based on sub-wavelength patterning have major potential for realizing arbitrary control of the wavefront of the diffracted light by achieving local control of the phase, amplitude and polarization. While our prototypes are based on optical antenna array the concepts are more general and can also use sub-wavelength spaced dielectric resonator array. We discuss novel devices based on this technique; a salient feature is the ability to create often with a single digital mask an arbitrary analog phase profile. A variety of flat optical components, including lenses, polarizers, vortex plates, coatings, holograms and couplers with polarization invariant coupling efficiency will be presented. Our ultimate vision is an optical phased array with fast wavefront tuning capabilities, including beam steering, on a nanosceocn time scale or shorter.