基于混合石墨烯-二氧化钒超材料的太赫兹可调宽带吸收器  

Broadband Tunable Terahertz Absorber Based on Hybrid Graphene-Vanadium Dioxide Metamaterials

作　　者：李辉 余江[1] 陈哲 Li Hui;Yu Jiang;Chen Zhe(School of Information,Yunnan University,Kunming,Yunnan 650500,China)

机构地区：[1]云南大学信息学院,云南昆明650500

出　　处：《中国激光》2020年第9期116-126,共11页Chinese Journal of Lasers

基　　金：国家自然科学基金(61162004)。

摘　　要：提出了一种基于混合石墨烯-二氧化钒超材料的可切换多功能太赫兹宽带吸收器的有效设计。由于单元结构的对称性,该吸收器在电磁波垂直入射时具有极化不敏感特性,并且在宽入射角范围内仍能保持良好的吸收性能。数值仿真结果表明:利用相变材料二氧化钒独特的从绝缘体到全金属态的过渡特性,通过调节其电导率可以动态地调谐宽频吸收谱的幅值。通过施加外部偏置电压来调整石墨烯的费米能级,可将宽频吸收光谱的峰值吸收率从0.226调整至0.992。通过同时改变两个独立可控的参数(二氧化钒的电导率和石墨烯的费米能级),所提出的器件能够在宽频范围内的透明绝缘介质、全反射器和宽带吸收器之间切换。所设计的系统可扩展至红外和可见光波段,为实现高性能太赫兹设备提供了一种新的设计思路。We proposed an effective design of multifunctional switchable broadband terahertz absorber based on hybrid graphene-vanadium dioxide metamaterials. Due to the symmetry of the unit cell, the absorber has polarization-insensitive properties when electromagnetic waves are incident perpendicularly, and can still maintain excellent absorption performance over a wide range of incident angles. Numerical simulation results show that the amplitude of the broadband absorption(from 1.69 THz to 3.21 THz) can be dynamically adjusted by adjusting the conductivity of the vanadium dioxide due to its unique transition characteristics from insulator to metal. Furthermore, by applying an external bias voltage to adjust the Fermi energy of graphene, the peak absorptance of the proposed absorber in the same broadband can be dynamically tuned from 0.226 to 0.992. By altering the two independently controllable parameters(the conductivity of vanadium dioxide and graphene′s Fermi energy) simultaneously, the proposed device can be switched among a transparent insulating dielectric, a perfect reflector, and a broadband absorber in a wide frequency range. The designed system can be extended to the infrared and visible bands, offering a new method for high-performance terahertz devices.

关 键 词：材料 超材料 吸收 石墨烯 二氧化钒 极化不敏感 

分 类 号：TB34[一般工业技术—材料科学与工程]