Dynamically adjustable high-Q quasi-bound state in the continuum based on Si gratings and graphene hybrid system

Two quasi-bound states in the continuum (BICs) are achieved by breaking the symmetry of grating spacing, grating width, and grating height in the infinitely long periodic Si grating and graphene hybrid system. Firstly, the relationship between three types of asymmetry and the Q factor was determined, and two BICs were classified and discussed. Next, an ambient refractive index sensor is designed utilizing the quasi-BIC; this sensor exhibits an outstanding sensitivity of S = 148.525 THz/RIU, with a maximum figure of merit (FOM) exceeding 19471. Finally, the influence of graphene Fermi energy levels on reflection and transmission spectra is analyzed, and a quasi-BIC is fabricated simply by controlling the Fermi energy levels of graphene without breaking other symmetry parameters. Compared with traditional methods, it provides dynamic regulation capabilities that traditional methods lack by adjusting structural parameters, highlighting its strong potential in practical applications.