Dynamically Programmable Terahertz Holographic Metasurface using CMOS IC Tiling

In this article, we design and demonstrate a multi-functional, digitally programmable metasurface at 0.3 THz fabricated using industry standard 65 nm CMOS (complementary metal oxide semiconductor) process. Each metasurface tile consists of 12×12 periodic array of unit cells and is later tiled to create a 2×2 array. This scalable approach helps to create larger programmable apertures without any overhead on cost and performance. Each unit cell in the metasurface is a programmable multi-split-ring resonator consisting of eight MOSFETs at the capacitive gaps. These transistors act as dynamically programmable digital switches which alter both amplitude and phase transmission properties of the metasurface independently. We experimentally demonstrate multi-functional applications namely, high-speed beam modulation with a switching ON/OFF ratio of ~25 dB at a maximum clock speed of 5 GHz and beamforming capability of ± 30°. In addition, we also simulate and experimentally verify spatial wavefront manipulation using binary-amplitude-only holography technique at 0.3 THz.