A multilayer patterned graphene metamaterial composed of rectangular graphene, square graphene, and X-shaped graphene is proposed to achieve dual plasmon-induced transparency (PIT) at terahertz frequency. The coupled mode theory calculations are highly consistent with the finite-difference time-domain numerical results. Interestingly, a photoelectric switch has been realized, whose extinction ratio and modulation degree of amplitude can be 7.77 dB and 83.3% with the insertion loss of 7.2%. In addition, any dips can be modulated by tuning the Fermi levels of three graphene layers with minor or ignorable changes of the other two dips. The modulation degrees of frequency are 8.0%, 7.4% and 11.7%, respectively, which can be used to design a triple-mode frequency modulator. Moreover, the group index of the multilayer structure can be as high as 150. Therefore, it is reasonable to believe that a multifunctional device can be realized by the proposed structure.

中文翻译：

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多层图案化石墨烯超材料中基于双PIT的光电开关和三模频率调制器。

提出了一种由矩形石墨烯，正方形石墨烯和X形石墨烯组成的多层图案化石墨烯超材料，以在太赫兹频率下实现双等离激元诱导的透明性（PIT）。耦合模理论的计算与时域有限差分数值结果高度一致。有趣的是，已经实现了一种光电开关，其消光比和振幅调制度可以为7.77dB和83.3％，插入损耗为7.2％。此外，可以通过调整三个石墨烯层的费米能级来调节任何浸入，而其他两个浸入的变化很小或可忽略。频率调制度分别为8.0％，7.4％和11.7％，可用于设计三模频率调制器。此外，多层结构的基团指数可以高达150。