Reconfigurable step-zoom metalens without optical and mechanical compensations.

A polarization-dependent metasurface that consists of nanobrick arrays with spatial varying dimensions in two orthogonal directions has shown independent phase control ability, which paves a new way to design a reconfigurable step-zoom lens with two different focal lengths depending on the polarization states of an incident beam. In this paper, we report a highly integrated step-zoom metalens with dual focal lengths based on double-sided metasurfaces sitting on a transparent substrate. By assigning the focal power and balancing the aberrations between the front and rear metasurfaces, a large field-of-view ( ± 20°) step-zoom metalens corrected for monochromatic aberrations was designed, and its high performance (nearly diffraction-limited image quality for both on-axis and off-axis imaging) was verified by full-wave numerical simulations. More interestingly, the image plane of the designed metalens keeps unchanged after the zoom switching, which will bring great convenience for practical applications. With the advantages such as ultra-compactness, flexibility, and simplicity, the proposed metalens indicates the potential in the fields that require highly integrated zoom imaging and beam focusing without optical and mechanical compensations.