Video-speed Graphene Modulator Arrays for Terahertz Imaging Applications

TL;DR

This paper presents a large-format, high-speed graphene-based THz modulator array enabling reconfigurable imaging and spectroscopy, overcoming previous trade-offs between modulation efficiency and switching speed for advanced THz applications.

Contribution

The development of a 256-pixel graphene THz modulator array with 1 kHz switching speed and demonstrated imaging capabilities is a novel advancement.

Findings

Achieved high-frame-rate reconfigurable THz transmission patterns

Identified charge relaxation and ion packing as limiting factors

Demonstrated a single-pixel THz camera for imaging large objects

Abstract

Electrically tuneable 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 active area. The trade-off between the efficient gating and switching speed, however, hinders the realization of these applications. Here, we demonstrate a large-format 256-pixel THz modulator which provides high-frame-rate reconfigurable transmission patterns. The time-domain and frequency-domain THz characterizations of graphene devices reveal the relaxation pathways of gate-induced charges and ion packing at graphene-electrolyte interface. The fundamental understanding of these limiting factors enables us to break the trade-off permitting switching frequencies up to 1 kHz. To show the promises of these devices, we demonstrate a single-pixel THz camera which allows spatial and spectroscopic imaging of large-area objects without any moving components. These results provide a significant advancement towards the achievement of non-invasive THz imaging systems using graphene-based platforms.