A novel structure for a THz absorber covering the THz band (0.1–10 THz) is presented. Exploiting nanographene disks and ribbons beside the dual-bias method, three modes of operation are introduced with the graphene gate biasing as the control parameter. The structure includes two layers consisting of graphene patterns on TOPAS dielectric and a thick gold plate at the bottom. The superior performance of the structure mainly relies on the use of feasible geometric patterns and the characteristics of graphene, while an evolutionary genetic algorithm is used to optimize a cost function defined based on four chemical potential values. In comparison with conventional structures, the device proposed herein offers an increased number of gate biases and thereby more degrees of freedom to achieve greater tunability. To model the proposed device, a recently developed circuit model approach is modified to include the dual-bias scheme introduced herein, enabling a very simple calculation of the referred input impedance of the device that lies at the heart of the design procedure. The input impedance required for impedance matching theory is matched with the free space incident medium (120π Ω) to maximize the absorption. Finally, the results from the MATLAB algorithm are verified against finite element method simulations using the CST simulator, confirming the validity and accuracy of the proposed design. According to both the circuit model representation and the full-wave numerical modeling, the presented device absorbs THz waves with an absorption ratio of more than 90% in three operational modes, viz. mode A (0.7–2.2 THz), mode B (5.3–6.6 THz), and mode C (7.4–8.4 THz). This increases its potential for use in numerous applications in the THz band such as sensors, detectors, modulators, and even optical processors.

中文翻译：

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可配置的两层四偏置石墨烯太赫兹吸收器

提出了一种覆盖太赫兹频带（0.1–10太赫兹）的太赫兹吸收器的新颖结构。除了采用双偏压方法外，还利用纳米石墨烯盘和碳带，介绍了三种操作模式，其中石墨烯栅极偏置为控制参数。该结构包括两层，这两层由TOPAS电介质上的石墨烯图案和底部的厚金板组成。该结构的优越性能主要取决于使用可行的几何图案和石墨烯的特性，而进化遗传算法则用于优化基于四个化学势值定义的成本函数。与常规结构相比，本文提出的器件提供了更多数量的栅极偏置，从而提供了更大的自由度以实现更大的可调性。要对建议的设备进行建模，对最近开发的电路模型方法进行了修改，使其包含本文介绍的双偏置方案，从而可以非常简单地计算位于设计过程核心的设备的参考输入阻抗。阻抗匹配理论所需的输入阻抗与自由空间入射介质（120πΩ  ）以使吸收最大化。最后，使用CST模拟器对MATLAB算法的结果进行了有限元方法仿真验证，证实了所提出设计的有效性和准确性。根据电路模型表示和全波数值建模，所提出的装置在三种工作模式下吸收THz波，吸收率超过90％。模式A（0.7–2.2 THz），模式B（5.3–6.6 THz）和模式C（7.4–8.4 THz）。这增加了其在太赫兹频段的众多应用中使用的潜力，例如传感器，检测器，调制器，甚至是光学处理器。