▎ 摘　　要

In this paper, a metamaterial absorber based on graphene is proposed, designed and simulated numerically using multilayer structures. Before describing our work, the performance response of a three-layer structure is studied concerning one cylinder as a unit cell. Then, by varying the chemical potential of graphene (Fermi level of graphene) by applying external potential, the center frequency of this absorber can be adjusted. We will prove that by increasing the number of cylinders as fundamental elements in the unit cell, the bandwidth is also adjustable. Also, the center frequency can be affected by changing the dimensions of fundamental elements. Considering the above-mentioned items, the structure is investigated through increasing the graphene layers in which the absorber's frequency response is wider respected to previous structures and the center frequency is adjustable as a result of variations in the chemical potential of graphene layers. It is shown that the proposed perfect absorber's central frequency shift through graphene's voltage variation is about 0.15 THz which can be increased to 0.3 THz by changing radius. In some of the introduced absorbers, the maximum value of the absorption has reached over 95%. The most important advantage of the proposed structure, which is the main purpose of designing terahertz metamaterial absorbers, is its adjustable bandwidth and center frequency, and simple fabrication.