A Broadband Switchable Metamaterial Absorber/Reflector Based On Multi-Laps Graphene Sheets in the Terahertz Band

Switchable metamaterial absorbers/reflectors (MAs/MRs) are important bifunctional electromagnetic devices and have been the subject of numerous scientific studies. However, there is a lack of bifunctional devices that operate in the terahertz band. Here, we theoretically propose a broadband switchable MA with many excellent properties, such as good thermal stability, high insensitivity to inferior film quality of the graphene, excitation polarization and wide incident angles, and outstanding structural parameter tolerance. The bandwidth of the proposed broadband MA is 3.4 THz with an absorptivity over 90% in the frequency band of 1.6-5 THz. The proposed absorber can switch to a reflector with a reflectivity over 93% by tuning the chemical potential of the graphene and reducing the temperature. Therefore, the switching intensity of the proposed MA exceeds 83%. The physical mechanisms of the broadband absorption of the proposed structure are investigated using the impedance matching theory and the multiple reflection interference theory. The reflection mechanism of the proposed broadband reflector is discussed by analyzing the effective parameters. The absorption and switching mechanism are theoretically investigated by performing detailed numerical calculations to analyze the surface loss intensity, electric field, and magnetic field. These findings can accelerate the development of terahertz broadband switchable devices.

Automated summary

In this theoretical study, a broadband switchable metamaterial absorber with excellent properties is proposed, achieving over 90% absorptivity and over 93% reflectivity in the terahertz band. The switching intensity exceeds 83% by tuning the chemical potential of graphene. Physical mechanisms and reflection mechanisms are investigated through impedance matching theory and detailed numerical calculations, accelerating the development of terahertz broadband switchable devices.