Multi-functional coding metasurface for dual-band independent electromagnetic wave control.

Multi-functional metasurfaces have exhibited powerful abilities of manipulating electromagnetic (EM) wave in predetermined manners, largely improving their information capacities. However, most works are implemented with EM functions controlled by one of the intrinsic properties of EM wave, such as polarization, frequency, etc. Herein, we propose a coding scheme to design a broadband and high-efficient multi-functional metasurface independently controlled by both frequency and polarization. To achieve this goal, we design anisotropic coding particles to realize independent phase functions and polarization-selectivity in the microwave region. Meta-atoms are finally optimized to exhibit 2-bit phase responses insensitive to incident polarization in the X-band while showing a 1-bit phase shift sensitive to incident polarization in the Ku-band. As a proof of concept, a metasurface is configured as an isotropic lens in the X-band, whereas the metasurface is designed as an anisotropic beam deflector in the Ku-band with or without polarization-conversion functionality dependent on the input polarization. The measured results, which agree well with the simulated ones, show excellent performances in the designed dual bands. Such a multi-functional coding metasurface may provide a flexible and robust approach to manipulate EM wave of multiple frequencies, as well as to integrate diverse functionalities into a single flat device.