Wang Tongling, Cao Maoyong, Zhang Huiyun, Zhang Yuping
Appl Opt. 2018 Nov 10;57(32):9555-9561. doi: 10.1364/AO.57.009555.
In this paper, the tunable properties of metamaterial absorbers based on 3D Dirac semimetal films (DSFs) in the terahertz (THz) regime are discussed in theory. We consider the absorbers with square-shaped, circular-patch, and cross-shaped resonators. These resonances are theoretically polarization-insensitive at normal incidence because of their 90° rotational symmetry and can achieve perfect absorption in numerical simulation. We then introduce dual-band and broadband absorbers by combining two DSF-based square-shaped (or circular-patch) resonators into one unit cell with different sizes. Unlike with a conventional metal-based absorber, the absorption of a DSF-based absorber can be dynamically tuned by varying the Fermi energy instead of refabricating the structures. Moreover, the DSFs can be regarded as a "Salisbury screen" of an absorber to block the transmission at the THz frequencies, which can be more convenient than graphene in the application of a tunable absorber. Our designs have potential applications in various fields such as sensors, thermal detectors, and imagers.
本文从理论上讨论了基于三维狄拉克半金属薄膜（DSF）的太赫兹（THz）波段超材料吸收体的可调谐特性。我们考虑了具有方形、圆形贴片和十字形谐振器的吸收体。由于这些谐振器具有90°旋转对称性，理论上在垂直入射时对偏振不敏感，并且在数值模拟中可以实现完美吸收。然后，我们通过将两个基于DSF的方形（或圆形贴片）谐振器组合到一个具有不同尺寸的单元胞中，引入了双频和宽带吸收体。与传统的基于金属的吸收体不同，基于DSF的吸收体的吸收可以通过改变费米能来动态调谐，而无需重新制造结构。此外，DSF可以被视为吸收体的“索利斯伯里屏”，以阻挡太赫兹频率下的传输，这在可调谐吸收体的应用中比石墨烯更方便。我们的设计在传感器、热探测器和成像仪等各个领域具有潜在应用。
