3-D Manipulation of Dual-Helical Electromagnetic Wavefronts With a Noninterleaved Metasurface

While electromagnetic (EM) metasurfaces have been extensively studied for wavefront manipulations, the real 3-D manipulation of wavefront remains challenging. In this article, an advanced strategy of noninterleaved multitasked metaplexer for 3-D manipulation of dual-helical EM wavefronts is reported. We first develop a general method to derive the metasurface phase distribution required to form the desired 3-D electric field patterns. Then, the spin-decoupled meta-atoms are designed to achieve this goal and further increase the degrees of freedom in EM manipulation. As a proof of concept, cascaded multiplane digital images in the propagation direction are employed as the 3-D wavefronts, which are encoded into the spin-decoupled meta-atoms array, making the outputting circularly polarized waves carrying different image information at different planes. Both the simulations and experiments verify the desirable 3-D wavefront manipulation capacities of our strategy for dual-helical states. Besides, this scheme can be further extended to achieve arbitrary energy allocation in 3-D space for dual-helical EM waves. Our strategy paves an alternative route for applications such as multiple-input multiple-output (MIMO) communications, multitarget radar detection, information storage, as well as 3-D microwave imaging.