Solid-state intensity modulator based on a single-layer graphene-loaded metasurface operating at 2.2 THz

We demonstrate a free-standing solid-state terahertz intensity modulator operating at 2.2 THz that achieves a modulation depth greater than 68% of the intensity of the transmitted radiation using a single-layer graphene-metal metasurface. We employ a brickwork antenna structure because of its potential for high modulation speed and large modulation depth. An equivalent circuit model for the brickwork antenna structure has been developed to optimize the geometric antenna parameters for the desired frequency response. The device has been fabricated and characterized using terahertz time-domain spectroscopy. By gating the graphene, the optical response of the device is modulated electronically. This results in a large change in the measured transmittance.