Programmable topological metasurface to modulate spatial and surface waves in real time

We propose a programmable topological metasurface to integrate intelligent modulations of spatial and surface waves. A general design method is presented to design the programmable metasurface elements with PIN diodes. The surface waves can be controlled to propagate along the topological domain-wall interface by programming the C₃-symmetry elements, while the spatial waves are modulated by the patterns of C₆-symmetry elements. By independently controlling the bias voltages of meta-elements, the programmable topological metasurface can generate different coding patterns with distinct combinations of C₃- and C₆-symmetries in real time, respectively achieving the dynamical manipulation of the surface- and spatial-wave by using distinct element states in a time-division manner. To validate the modulation performance, we perform both near- and far-field tests with different coding patterns. Experimental results demonstrate good agreement with numerical simulations, thereby showcasing the flexible manipulations of surface waves and spatial waves by the topological metasurface. The proposed metasurface opens up new possibilities for multifunctional metadevices, which hold great potentials for future wireless communications and smart sensing systems.