Recent progress in terahertz modulation using photonic structures based on two‐dimensional materials

Abstract

Terahertz (THz) technology has attracted great attention in the past few decades for its unique applications in various fields, including spectroscopy, noninvasive detection, wireless communications, and imaging. In parallel to this, the practical, fast, and broadband modulation of THz waves is becoming indispensable. Two-dimensional (2D) materials exhibit unusual optical and electrical properties, which has prompted tremendous interest and significant advances in THz modulation. This review provides the recent progress in 2D materials-based THz modulators, outlining the operating principles, including all-optical, electro-optic, magneto-optic, and other exotic mechanisms. We focus on the recent advances in THz modulation by the designed photonic structures, such as heterostructure, metamaterial, capacitor, optical cavity, and waveguide integration. Lastly, we discussed the challenges and opportunities for 2D materials-based THz modulators and presented our prospects for the future development.

Emerging MoS2 Wafer-Scale Technique for Integrated Circuits

“…Based on previous reports, the physical properties of intrinsic MoS 2 are closely related to the film thickness [ 14 , 15 ]. The single-layer MoS 2 film is a semiconductor with a direct band gap of 1.83 eV, which can produce strong photoluminescence and electroluminescence [ 16 , 17 ]. At present, the threshold voltage of single-layer MoS 2 synthesized by chemical vapor deposition technology is less than − 50 V, showing prominent n-type conductivity characteristics [ 16 , 18 ].…”

Strong In-Plane Anisotropic SiP2 as a IV–V 2D Semiconductor for Polarized Photodetection

“…In-plane anisotropic two-dimensional (2D) materials are attracting considerable research interest, owing to their extensive applications in the anisotropic multifunctional devices, such as linearly polarized pulse generators, polarization imaging, and polarization-sensitive photodetector. − The low-symmetry 2D materials with anisotropic structures and strong light–matter interaction are increasingly demanded to achieve high-performance polarization-sensitive optoelectronic devices. As a pioneer low-symmetry 2D semiconductor, black phosphorus (BP) features a puckered honeycomb structure with a high carrier mobility, excellent light absorption, adjustable direct band gap, and strong in-plane anisotropy. − A lot of effort has been devoted to developing polarized optoelectronic devices based on BP . Unfortunately, each phosphorus atom in BP exposes lone-pair electrons, which will induce the oxidation and degradation in ambient under light illumination. − Therefore, the ambient instability of BP has restricted its widely practical applications.…”

Novel switching of liquid crystals for use in rapid THz phase shifters discovered from the dimensional effects of electrodes

“…THz technology is rapidly advancing to meet the needs of next-generation wireless communication systems beyond 5G 1,2 . Accordingly, THz modulation technology has become indispensable for various applications 3,4 . For example, arrays of phase shifters can be used to form THz beams.…”