A Tunable Metasurface with Switchable Functionalities: From Perfect Transparency to Perfect Absorption

A thin screen exhibiting dynamically switchable transmission/absorption functionalities is highly desired in practice. However, a trilayer transmissive metasurface with active elements controlled in a uniform manner cannot exhibit independently controlled transmission and absorption properties due to intriguing interplays between the scattering and absorbing properties in systems exhibiting inversion symmetries. This motivates to employ the coupled-mode theory to establish a generic phase diagram for such transmissive metasurfaces with active elements loaded in different layers tuned independently and to guide researchers design tunable metadevices with completely decoupled transmission/absorption responses. Based on such a phase diagram, a microwave metasurface is designed/fabricated with PIN diodes incorporated, and it is experimentally demonstrated that its functionality can switch from perfect transparency to perfect absorption, controlled by external voltages applied across the diodes. In addition to finding immediate applications in practice (e.g., smart radomes), the results of this study also provide a new type of tunable meta-atom for building metasurfaces with flexible wave-front control abilities.