Digital Coding Metasurfaces: From Theory to Applications

The concept of "coding metasurfaces" was first put forward in 2014 and has developed rapidly during the past few years, originating several intriguing ramifications. The essential underlying idea is to discretize the local geometry, constitutive parameters, and electromagnetic (EM) responses (e.g., the phase, amplitude, and polarization) so that they can be represented via sequences of digits (e.g., "0" and "1"). This concept breaks the boundaries between traditional analog and digital devices, bridging the physical and information worlds, and opens up new perspectives in the design of metasurfaces.