Video-Speed Graphene Modulator Arrays for Terahertz Imaging Applications
Yury Malevich, M. Said Ergoktas, Gokhan Bakan, Pietro Steiner, Coskun Kocabas
Abstract
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- and 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.