A programmable metasurface with dynamic polarization, scattering and focusing control

TLDR

Programmable metasurfaces can exhibit diverse electromagnetic responses, enabling multiple functionalities on a single large‑scale surface. The study aims to demonstrate reconfigurable polarization conversion by exploiting the metasurface’s anisotropic characteristics. This is achieved with a PIN‑diode‑integrated unit cell that provides binary phase coding, optimized via a genetic algorithm and accelerated by an inverse FFT to tailor scattering for plane and point sources. Simulations and experiments confirm anomalous reflection, diffusion, beam steering, and beam‑forming, with real‑time switching among these modes enabled by an FPGA, indicating strong application potential.

Abstract

Abstract Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications.