Quasi-bound state in the continuum based strong light confinement in graphene metasurfaces

Abstract

The bound state in the continuum (BIC) is exploited to metasurfaces for the purpose of arising strong confinement of light and high quality (Q) factor resonances. In this paper, a BIC symmetry-protected metasurface consisting of rectangular graphene patches is synthesized and realistically modeled with intrinsic losses in a far-infrared regime. The quasi-BIC with three asymmetry approaches is applied to attain strong tailored confinement of the incident light, and the resulting resonances with tailored line widths and selective confinement of light are exhibited. Asymmetry parameters of length, rotation, and material feature of chemical potential regulate dual specifications of resonance linewidth and intensity. Efficiency analysis of the results illustrates that rotation asymmetry is the foremost among the three suggested methods, and it establishes the highest Q-factor of 945 with an achievable asymmetry parameter of 5.5%. The high Q and tunable resonances realized in the graphene quasi-BIC metasurfaces promise various practical applications in the infrared spectra, such as narrow band filters, sensors, optical switches, and light-matter interaction platforms.