A graphene-metal metasurface for terahertz modulation with a depth of several orders of magnitude

Next-generation communication systems necessitate rapid and efficient control of terahertz (THz) signals to encode data streams. Graphene-based metamaterials have emerged as promising candidates for effective THz modulation owing to graphene’s large electrically controllable conductivity. However, a significant challenge arises from graphene’s inability to achieve full depletion at the Dirac point, limiting the transmission modulation depth in most LC-resonant metasurface modulators. To overcome this limitation, we exploit the interference of Fresnel reflection components from the metasurface and the substrate and propose tuneable capacitors as active elements. Our study presents single-layer, all-solid-state, graphene-metal metasurface modulators operating in the THz range, characterized using terahertz time-domain spectroscopy. Our approach enables us to achieve intensity modulation of more than four orders of magnitude. These findings underscore the potential of graphene-based metamaterials in advancing THz communication technologies.