Video-Speed Graphene Modulator Arrays for Terahertz Imaging Applications

Electrically tunable high mobility charges on graphene yield an efficient electro-optical platform to control and manipulate terahertz (THz) waves. Real-world applications require a multiplex THz device with efficient modulation over a large area. The trade-off between the efficient gating and switching speed, however, hinders the realization of these applications. In this Letter, we demonstrate a large-format 256-pixel THz modulator that provides high-frame-rate reconfigurable transmission patterns. The time- A nd frequency-domain THz characterizations of graphene devices reveal the relaxation pathways of gate-induced charges and ion packing at the graphene-electrolyte interface. The fundamental understanding of these limiting factors enables breaking the trade-off permitting switching frequencies up to 1 kHz. To show the promises of these devices, we demonstrate a single-pixel THz camera that allows spatial and spectroscopic imaging of large-area objects without any moving components. These results provide a significant advancement toward the achievement of noninvasive THz imaging systems using graphene-based platforms.