High-Contrast Terahertz Wave Modulation by Gated Graphene Enhanced by Extraordinary Transmission through Ring Apertures

TLDR

Graphene’s gate‑controllable terahertz transmission makes it a promising high‑speed modulator material, yet single‑layer devices have shown only modest on/off ratios because of weak THz absorption. By placing metallic ring apertures above gated single‑layer graphene, the authors achieved ~50 % amplitude modulation and a seven‑fold near‑field enhancement, yielding CMOS‑compatible modulators with large on/off ratios, high speed, and tunable operation for THz communications, imaging, and sensing.

Abstract

Gate-controllable transmission of terahertz (THz) radiation makes graphene a promising material for making high-speed THz wave modulators. However, to date, graphene-based THz modulators have exhibited only small on/off ratios due to small THz absorption in single-layer graphene. Here we demonstrate a ∼50% amplitude modulation of THz waves with gated single-layer graphene by the use of extraordinary transmission through metallic ring apertures placed right above the graphene layer. The extraordinary transmission induced ∼7 times near-filed enhancement of THz absorption in graphene. These results promise complementary metal–oxide–semiconductor compatible THz modulators with tailored operation frequencies, large on/off ratios, and high speeds, ideal for applications in THz communications, imaging, and sensing.