A simple structured and homo-frequency point mode switchable THz full-space metasurface based on temperature-controlled vanadium dioxide

• Published in: Optics and laser technology 2024-03, Vol.170, p.110233, Article 110233
• Main Authors: Qiao, Xiaozhen, Wang, Aofei, Xiao, Wenguang, Zhang, Jingyi, Xia, Xing, Liang, Yongkang, Wang, Jinchao, Jiang, Ping
• Format: Article
• Language: English
• Subjects: Focusing vortex generator; Homo-frequency point; Mode switchable metasurface; Near-field imaging; Vanadium dioxide
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2023.110233

•Simple structure: Our proposed meta-atomic structure consists of only a layer of vanadium dioxide film, a polyimide substrate, and a silicon column with ellipsoidal columns cut off, which is a simple structure conducive to its processing and preparation in the laboratory.•Realization of the switching between reflection mode and transmission mode is at same frequency point: Our proposed meta-atom can realize flexible switching between reflection mode and transmission mode at same frequency point. As far as we know, almost all reported mode switchable metasurfaces that achieve full space optical functions are achieved at different frequency points. However, the phase distribution is related to frequency, which means that if the frequency is different, the arrangement of the metasurface is also different. Then corresponding array arrangements must be made for the elemental atoms at different frequency points, which is not conducive to integrated practical applications in the future. Our suggested design concept of homo-frequency points provides a worthwhile direction for future research of full-space functional devices.•High Efficiency in a wide frequency bandwidth: Our proposed meta-atom has high efficiency at a wide operating bandwidth. Under transmission mode, the transmittance efficiency of the meta-atom in the frequency range of 1.310 THz−1.490 THz is above 0.8. Under reflection mode, the reflection efficiency of the meta-atom in the frequency range of 1.310 THz−1.347 THz is also above 0.8. And all of them can realize the full coverage of 2π phase. In the frequency range of 1.310 THz−1.347 THz, the transmittance and reflectance effects are maintained at a high level, which also shows that the efficient operation of the transmittance and reflectance modes at the same frequency point can be realized in this frequency range. Terahertz (THz) full-space metasurfaces have attracted great attention in the field of modern communication systems due to their inherent advantages in electromagnetic (EM) wave manipulation. However, nearly all the reported full-space metasurfaces are realized by multilayer dielectric cascade structures. Furthermore, for mode switchable metasurfaces, reflection and transmission modes are always switched at different frequency points, which limits their application prospects. In this paper, we propose a full-space THz metasurface that can switch between reflection and transmission modes at the same frequency point only by controlling a