Tunable magnetoplasmons for efficient terahertz modulator and isolator by gated monolayer graphene.

Terahertz (THz) technology has been a promising tool for sensing, spectroscopy, imaging, and communication. However, only few devices have shown efficient performance for future THz technology. Herein, we propose a device based on tunable magnetoplasmons in gated monolayer graphene for THz wave modulation and isolation. The relative transmission and the Faraday rotation angle of the device have been calculated by combining the Fresnel method with the voltage-dependent Drude model. Our results suggest that a superior modulation depth and giant Faraday rotation due to the cyclotron effect in the classical regime by intraband transitions in graphene offer an effective, uniform, and flexible tunability for THz wave. And the modulating and isolating manipulations by graphene can range from 0 to 2 THz, with electron-hole asymmetry originating from variable scattering rate of magnetoplasmons. Moreover, the thickness effect of the thin substrate is also studied for better performance of the device, taking advantage of the unavoidable Fabry-Perot (F-P) effect. This work demonstrates a pathway for efficient THz modulator and isolator based on the magneto-optical polarization effect in graphene.