An All-Dielectric Defective Terahertz Metasurface based on Bound States in the Continuum

The idea of terahertz resonance with a high quality (Q) factor has garnered significant interest in recent years due to its crucial function in various applications. A novel approach, namely the all-dielectric metasurface composed of two cuboids with an air hole, to address the challenges of achieving high-Q resonance is proposed in this paper. The metasurface proposed in this study employs quartz as the substrate material and silicon as the cuboid material. Asymmetric clusters are created by manipulating the height of air hole in cuboid, which leads to the activation and identification of additional high-Q resonance that are regulated by bound states in the continuum (BIC). By multipole decomposition, we conduct a numerical analysis to investigate the major electromagnetic excitations in this resonance, and find that the resonance is dominated by electric quadrupole (Qe), respectively. The study also examines the transmission spectra of metasurface with varying structural parameters. When the metasurface functions as a transmittance sensor, its Q-factor is 1.78 × 104, which are obtained under$K$= 1 μm.