基于金属-石墨烯多层结构的可调谐无偏振完美吸收器

Tunable Polarization-Independent Perfect AbsorberBased on Metal-Graphene Multilayers

提出一种基于金属-石墨烯多层结构并可在太赫兹区域实现从双频、多频到宽频的完美超材料吸收器.该超材料吸收器由含金电极的2种不同半径的石墨烯圆盘组成,并且每个石墨烯圆盘中的费米能级可通过加在金电极和金基底上的门电压独立控制,从而可实现其共振吸收频率的独立或同步调控,这样在不改变吸收器几何尺寸的情况下,可得到双频、多频和宽频吸收的动态调控.此外,由于结构的几何对称性,吸收器对入射光偏振不敏感,适合较大的入射倾角.结构简单和可调控性使单层石墨烯吸收器在传感、探测、隐身等领域有着潜在的应用价值.

In this paper,a new dual-band to multi-band to broad-band perfect metamaterial absorber based on metal-graphene multilayers is proposed in the terahertz region.The unit cell of proposed metamaterial absorber consists of two graphene discs of different radii with gold electrodes on the top and are separated by a dielectric spacer from the gold film on the bottom.In our proposed absorber,the Fermi energy in each graphene disc can be independently controlled by the gated voltages applied on the gold electrodes and gold substrates,thus achieving independent or synchronous regulation of its resonance absorption frequency.As a result,the dynamically tunable dual-band to multi-band to broad-band absorption can be obtained without changing the geometric parameters of the structure.In addition,owing to the symmetry of the structure,the proposed absorber is insensitive to polarization.Due to simple design and flexible regulation,our proposed single-layer graphene absorber can be applied in many metamaterial fields,such as sensing,detecting,and cloaking objects.