Soleymani Ali, Meymand Roya Ebrahimi, Granpayeh Nosrat
Appl Opt. 2020 Mar 20;59(9):2839-2848. doi: 10.1364/AO.383637.
In this work, we have done an extensive study on broadband near-perfect absorbers consisting of single-layered and non-structured graphene loaded with periodical arrays of dielectric bricks, including square and elliptical bricks. We also propose and investigate circular cylinder, rectangular brick, and racecourse dielectric structure. Moreover, the calculated ${z}$z component of the electric field enables us to understand the physical mechanism of resonance absorption. Furthermore, we also studied and proposed a new absorber with periodical arrays of stepped rectangle dielectric structure. We could achieve a broadband absorption from 1.6 to 4.2 THz, with a bandwidth of 2.6 THz and absorption over 90%. The proposed absorber is also tunable; the tunability of the terahertz (THz) broadband absorber is achieved via changing the external gate voltage to modify the Fermi energy of graphene. Also, we compared the results and absorption spectra of different dielectric structures. This THz metamaterial structure can be used in different THz applications such as cloaking, sensing, detection, and imaging.
在这项工作中，我们对由加载有介电砖（包括方形和椭圆形砖）周期性阵列的单层且无结构的石墨烯组成的宽带近完美吸收体进行了广泛研究。我们还提出并研究了圆柱、矩形砖和跑道形介电结构。此外，计算得到的电场的${z}$分量使我们能够理解共振吸收的物理机制。此外，我们还研究并提出了一种具有阶梯矩形介电结构周期性阵列的新型吸收体。我们可以实现从1.6到4.2太赫兹的宽带吸收，带宽为2.6太赫兹，吸收率超过90%。所提出的吸收体也是可调谐的；太赫兹（THz）宽带吸收体的可调谐性是通过改变外部栅极电压来改变石墨烯的费米能实现的。此外，我们比较了不同介电结构的结果和吸收光谱。这种太赫兹超材料结构可用于不同的太赫兹应用，如隐身、传感、检测和成像。
