High-Speed Modulations of Guided Terahertz Waves via 2DEG Tiny Metasurfaces

Metasurfaces have emerged as fascinating planar optical components and devices, and, in particular, active metasurfaces confer more multifunctional expansions. However, the metasurface research has mainly focused on operating the light in free space, which hardly satisfies the system-level compactness and miniaturization. The potential of the metasurface for guided wave modulation remains to be further developed. Here, an integrated electronic device is reported by embedding a tiny metasurface, which consists of several patterned 2D electron gas (2DEG) microstructures in a waveguide. This device suppresses excessive parasitism to improve the modulation speed and enhances the electromagnetic field interaction to improve the modulation efficiency. It is experimentally demonstrated that high-speed modulations are electrically excited by the guided terahertz waves on a time scale of 40 ps via the tiny metasurface. This scheme represents a new platform for compact and high-speed integrated electronics.