▎ 摘　　要

Graphene can be utilized in designing adjustable terahertz (THz) devices due to its variability of sheet conductivity. In this paper, a broadband adjustable graphene absorber operating at THz frequencies is proposed. By changing the Fermi level of the graphene from 0 eV-1 eV, the absorption relative bandwidth and absorption rate can be adjusted from 20%-90.32% and from 0-100%, respectively. The Fermi level of the graphene can be adjusted actively by adjusting the bias voltage on the graphene layer or by chemical doping, which enables us to electrically or chemically control the absorption performance flexibly. We use the multi-reflection interference theory to investigate the physical insight of the proposed absorber under normal incidence and oblique incidence. This paper is the first to interpret oblique incidence using the multi-reflection interference theory. From this, we can infer the value of effective permittivity of the absorber under oblique incidence, which provides great help for the design of an absorber. The calculated and simulated results are in excellent agreement.