Huang Jin, Li Jining, Yang Yue, Li Jie, Li Jiahui, Zhang Yating, Yao Jianquan
Opt Express. 2020 Jun 8;28(12):17832-17840. doi: 10.1364/OE.394359.
An actively tunable broadband terahertz absorber is numerically demonstrated, which consists of four identical vanadium dioxide (VO) square loops and a metal ground plane separated by a dielectric spacer. Simulation results show that an excellent absorption bandwidth of 90% terahertz absorptance reaches as wide as 2.45 THz from 1.85 to 4.3 THz under normal incidence. By changing the conductivity of VO, an approximately perfect amplitude modulation is realized with the absorptance dynamically tuned from 4% to 100%. This absorption performance is greatly improved compared with previously reported VO-based absorbers. The physical mechanisms of a single absorption band and the perfect absorption are elucidated by the wave-interference theory and the impedance matching theory, respectively. Field distributions are further discussed to explore the physical origin of this absorber. In addition, it also has the advantages of polarization insensitivity and wide-angle absorption. The proposed absorber may have many promising applications in the terahertz range such as modulator, sensor, cloaking and optic-electro switches.
数值演示了一种有源可调谐宽带太赫兹吸收器，它由四个相同的二氧化钒（VO）方形环和一个通过电介质间隔层与金属接地平面隔开的结构组成。仿真结果表明，在垂直入射下，该吸收器在1.85至4.3太赫兹范围内实现了高达2.45太赫兹的90%太赫兹吸收率的出色吸收带宽。通过改变VO的电导率，实现了近似完美的幅度调制，吸收率从4%动态调谐到100%。与先前报道的基于VO的吸收器相比，这种吸收性能有了很大提高。分别利用波干涉理论和阻抗匹配理论阐明了单吸收带和完美吸收的物理机制。进一步讨论了场分布以探究该吸收器的物理起源。此外，它还具有偏振不敏感和广角吸收的优点。所提出的吸收器在太赫兹范围内可能有许多有前景的应用，如调制器、传感器、隐身和光电开关。
