Abstract

Based on graphene metasurface, this paper proposes a broadband multifunctional reflective polarization converter in the terahertz regime. This converter was formed of periodic unit cells, and each cell comprises two gold resonant ribbons, two-layer graphene sheets, a dielectric spacer, and a ground plane. The results demonstrated that the converter presented dynamical multiple polarization-manipulating functions, such as linear-to-circular conversion and linear-to-linear conversion, by varying the Fermi energy of the graphene. For example, in the frequency range from 0.92 to 1.47 THz, the ultra-broadband cross-polarization conversion was obtained with a Fermi energy of 0 eV, and in the range from 0.55 to 1.26 THz, the ultra-broadband linear-to-circular polarization conversion was achieved by varying the Fermi energy with a tunable relative bandwidth of 78.5%. Finally, the physical mechanisms were determined by analyzing the equivalent circuits and current distributions. This polarization converter has the potential for future applications in electronic measurements, photonic design, and other optoelectronic systems.

Graphic abstract

中文翻译：

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基于石墨烯超表面的宽带多功能太赫兹偏振转换器

摘要

本文基于石墨烯超表面，提出了一种在太赫兹状态下的宽带多功能反射偏振转换器。该转换器由周期性晶胞组成，每个晶胞包含两个金谐振带，两层石墨烯片，一个介电垫片和一个接地层。结果表明，该转换器通过改变石墨烯的费米能，表现出动态的多重极化控制功能，例如线性至圆形转换和线性至线性转换。例如，在0.92至1.47 THz的频率范围内，费米能量为0 eV，在0.55至1.26 THz的范围内获得了超宽带交叉极化转换，超宽带线性至圆偏振转换是通过以可调相对带宽78.5％改变费米能量实现的。最后，通过分析等效电路和电流分布来确定物理机制。该偏振转换器具有在电子测量，光子设计和其他光电系统中未来应用的潜力。

图形摘要