Abstract
An actively tunable broadband terahertz absorber is numerically demonstrated, which consists of four identical vanadium dioxide (VO2) 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 VO2, 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 VO2-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.
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Citations
Jan 1, 2021·Optics Express·Hui LiJiang Yu
Oct 30, 2020·Optics Express·Yijun CaiJinfeng Zhu
Mar 18, 2021·Optics Express·Tong WuYachen Gao
Mar 18, 2021·Optics Express·Guozhang WuJianguo Liu
Jul 17, 2021·Optics Express·Man Zhang, Zhengyong Song
Jul 17, 2021·Optics Express·Youdan ZhangLibo Yuan