Cai Yijun, Guo Yongbo, Zhou Yuanguo, Huang Xindong, Yang Guoqing, Zhu Jinfeng
Opt Express. 2020 Oct 12;28(21):31524-31534. doi: 10.1364/OE.409205.
In this paper, we theoretically design a dual-band graphene-based terahertz (THz) absorber combining the magnetic resonance with a THz cold mirror without any metallic loss. The absorption spectrum of the all-dielectric THz absorber can be actively manipulated after fabrication due to the tunable conductivity of graphene. After delicate optimization, two ultra-narrow absorption peaks are achieved with respective full width at half maximum (FWHM) of 0.0272 THz and 0.0424 THz. Also, we investigate the effect of geometric parameters on the absorption performance. Coupled mode theory (CMT) is conducted on the dual-band spectrum as an analytic method to confirm the validity of numerical results. Furthermore, physical mechanism is deeply revealed with magnetic and electric field distributions, which demonstrate a totally different principle with traditional plasmonic absorber. Our research provides a significant design guide for developing tunable multi-resonant THz devices based on all-dielectric configuration.
在本文中，我们从理论上设计了一种基于石墨烯的双波段太赫兹（THz）吸收器，它将磁共振与太赫兹冷镜相结合，且无任何金属损耗。由于石墨烯的电导率可调，全介质太赫兹吸收器的吸收光谱在制造后可被主动调控。经过精细优化，实现了两个超窄吸收峰，其半高全宽（FWHM）分别为0.0272太赫兹和0.0424太赫兹。此外，我们研究了几何参数对吸收性能的影响。作为一种分析方法，对双波段光谱进行了耦合模理论（CMT）分析，以确认数值结果的有效性。此外，通过磁场和电场分布深入揭示了物理机制，这表明其原理与传统等离子体吸收器完全不同。我们的研究为基于全介质结构开发可调谐多谐振太赫兹器件提供了重要的设计指导。
