Arbitrarily polarized retro-reflections by anisotropic digital coding metasurface

We propose an anisotropic digital coding metasurface to realize arbitrarily polarized retro- reflections. With the theoretical support of generalized Snell's laws, the proposed coding metasurface shows excellent performance of retro-reflections through reflection phase design. A modified metallic Jerusalem cross structure is employed to achieve the required phase profile under oblique incidence due to its good performance in polarization isolation. By changing the length of coding particle's arms, the particle can be digitally named as '00', '01', '10' and '11' elements with different phase responses. Through special design of phase gradient, the coding metasurface can reflect incident waves backwards for arbitrary polarizations, which can be decomposed into transverse electric and transverse magnetic polarizations. A prototype was fabricated and measured. Both simulation and experiment results verify the good performance of the arbitrarily polarized retro-reflections by the metasurface.