Chen Mingming, Yang Xue-Xia
School of Communication and Information Engineering, Shanghai University, Shanghai, China.
Key Laboratory of Specialty Fiber Optics and Optical Access Networks, School of Communication and Information Engineering, Shanghai University, Shanghai, China.
Phys Chem Chem Phys. 2023 Aug 9;25(31):21074-21081. doi: 10.1039/d3cp02561f.
The multi-layer terahertz metasurfaces are designed to achieve polarization-insensitive electromagnetically induced transparency (EIT) effect and its sensing performance based on spoof localized surface plasmons (S-LSPs). The unit cell of the proposed metasurfaces is comprised of a metallic spiral (MS) structure, square metal frame (SMF) structure, and vanadium dioxide (VO) layer. The EIT effect is realized by the bright-bright coupling between spoof electric localized surface plasmons (S-ELSPs) and electric dipole, which can be proved by the multipole scattering theory. The maximum value of transmission amplitude at the transparent window is 0.91, and the modulation depth can reach 51% by adjusting the conductivity of VO. The theoretical results based on the two-particle model show excellent agreement with the simulated results. Moreover, the change of polarization angle has little effect on the EIT effect and the proposed metasurfaces show polarization-insensitive characteristics. The slow light effect of the proposed metasurfaces can also be dynamically controlled by tuning the conductivity of VO. Due to the high value of the transparent window, the proposed metasurfaces exhibit excellent sensing performance, and the sensitivity is 0.172 THz RIU. Our study provides a method for the fabrication of EIT metasurfaces and has a broad application prospect in slow light devices, sensors, and modulators.
多层太赫兹超表面旨在基于类局域表面等离子体激元（S-LSPs）实现偏振不敏感的电磁诱导透明（EIT）效应及其传感性能。所提出的超表面的单元结构由金属螺旋（MS）结构、方形金属框架（SMF）结构和二氧化钒（VO）层组成。EIT效应是通过类局域电表面等离子体激元（S-ELSPs）与电偶极子之间的亮-亮耦合实现的，这可以通过多极散射理论得到证明。透明窗口处的传输幅度最大值为0.91，通过调节VO的电导率，调制深度可达51%。基于双粒子模型的理论结果与模拟结果显示出极好的一致性。此外，偏振角的变化对EIT效应影响很小，所提出的超表面表现出偏振不敏感特性。所提出的超表面的慢光效应也可以通过调节VO的电导率来动态控制。由于透明窗口的值较高，所提出的超表面表现出优异的传感性能，灵敏度为0.172 THz/RIU。我们的研究为EIT超表面的制造提供了一种方法，在慢光器件、传感器和调制器方面具有广阔的应用前景。
