Controllable and Programmable Nonreciprocity Based on Detachable Digital Coding Metasurface

Abstract In traditional nonreciprocial devices and nonreciprocial metamaterials, the nonreciprocity functions are fixed and noneditable. Here, a detachable digital coding metasurface is proposed integrated with power amplifiers to realize controllable and programmable nonreciprocity, in which a metasurface element embedded with two amplifiers is designed and demonstrated. Based on the nonreciprocity of the unilateral transistors, a supercell structure is further presented composed of two opposite elements to obtain the controllable and programmable nonreciprocity characteristics. By applying distinct digital control signals (like “10,” “01,” and “11”) on the power amplifiers, the proposed metasurface can realize forward and backward nonreciprocal transmissions, and reciprocal transmission, respectively. An 8 × 10 metasurface is fabricated, which is divided into ten detachable unit pieces (with eight supercell elements on each piece) for easy assembling and control. The design of the detachable unit pieces promises more flexible functionalities and yields advantages in cost. The validation experiments are performed in both near and far fields, and the measured results show good consistency with theoretical designs and numerical simulations. Combined with the digital coding features of metasurfaces, it is believed that the proposed method has various potential applications in wireless communications and other intellectualized systems.