Performance comparison of two terahertz all-dielectric metasurfaces based on bound states in the continuum

In recent years, the concept of bound states in the continuum (BICs) in optics has become a research hotspot and has attracted the attention of many scholars. It provides an important physical mechanism for the generation of high -quality-factor optical resonance in high-refractive-index dielectric nanoparticles and all-dielectric metasurfaces. In this paper, two metasurfaces with the same structure of different materials are proposed. The resonant frequencies of the two structures are consistent, and the error is within 2.5 GHz. The quasi-BIC resonance is excited in the same way of breaking the symmetry. Subsequently, the electric field distribution, sensitivity, and figure of merit (FOM) of the two metasurfaces are analyzed, and sensitivities of 79.3 GHz/RIU and 72.4 GHz/RIU and the highest FOMs of 424.8 and 180.5, respectively, are achieved. These two all-dielectric metasurfaces are compared in this study, further confirming the advantages of all-silicon metasurfaces. (c) 2023 Optica Publishing Group