Multimode tunable terahertz absorber based on a quarter graphene disk structure

In this research work, in order to solve the unadjustability of traditional noble metal absorbers to meet the complex application requirements in the actual electromagnetic environment, we designed a simple tunable absorber based on graphene with tunable Fermi level. The performance of the proposed absorber is theoretically simulated by the finite difference time domain (FDTD) method. The proposed absorber has two perfect absorption peaks with high efficiency of 99.51% and 99.548% in its working band (90–155 μm). We have performed an in-depth analysis of the causes of perfect absorption and focused on the tunability of the absorber. The absorption frequency can be adjusted by controlling the relaxation time and Fermi level of graphene, and the same purpose can be achieved by changing the refractive index (relative dielectric constant) of the medium. In addition, we also explored the influence of the change of the top structure parameters on the absorption performance. The proposed absorber has the ability to adapt to different electromagnetic environments. In general, it can be flexibly regulated in practical applications, which will provide new possibilities for the development of many fields such as detection and communication.