Adjustable Deflection Metadevice Based on Alvarez Lens

Thanks to the capability of metasurfaces to sculpt light beams at sub wavelength scales, they provide amazing functionality that traditional lenses cannot match. Here, we have proposed and demonstrated by numerical simulation an approach to realize deflecting transmitted beams along x or y axis whose refraction angle is determined by relative displacement of two cascaded metasurfaces. The results prove that the refraction angle can be tuned precisely by the relative movement distance between the cascaded metasurfaces and the refraction angle can be changed along x axis (or y axis) by moving a metasurface along y axis (or x axis). The metasurfaces are developed using silicon nanopillars with spatially variant orientations based on Pancharatnam-Berry (PB) phase with illumination of right-handed circular polarized (RCP) light beams. The uniqueness of this metadevice with deflectable focal points may open a new avenue for imaging, optical tweezers, optical spanner and free space communication.