Yu Anqi
State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences 500 Yutian Road Shanghai 200083 China
University of Chinese Academy of Sciences No. 19 A Yuquan Road Beijing 100049 China.
RSC Adv. 2018 Jun 19;8(40):22286-22292. doi: 10.1039/c8ra02013b.
The localized electric field enhancement of graphene plasmon modes is limited by the duty cycle of graphene, the frequency, the absorption and the scattering rate. To obtain higher detectivity, higher field enhancement is required. While the absorption can be no larger than 100%, the scattering is an intrinsic limitation, and the frequency is designated, the duty cycle is the only parameter that can be designed freely to achieve high field enhancement. By etching graphene into periodic structures, reducing the duty cycle of graphene, the localized electric field can be enhanced as a result of the reduction of the active region. However, too small a duty cycle will weaken the coupling efficiency, which will reduce the absorption, and then the localized electric field can hardly be further enhanced. In this work, we propose to use the metallic split-mesh structure which will focus the incident radiation at the ends of the metallic bars. The absorption and the electric field will be greatly enhanced by placing graphene structures below the small holes formed by the metallic split-mesh structure.
石墨烯等离激元模式的局部电场增强受到石墨烯占空比、频率、吸收和散射率的限制。为了获得更高的探测率，需要更高的场增强。虽然吸收不能超过100%，散射是一个固有限制，且频率是确定的，但占空比是唯一可以自由设计以实现高场增强的参数。通过将石墨烯蚀刻成周期性结构，减小石墨烯的占空比，由于有源区的减小，局部电场可以得到增强。然而，占空比过小会削弱耦合效率，从而降低吸收，进而难以进一步增强局部电场。在这项工作中，我们建议使用金属裂环结构，该结构将入射辐射聚焦在金属条的端部。通过将石墨烯结构放置在金属裂环结构形成的小孔下方，吸收和电场将大大增强。
