Quasi-BIC-induced perfect absorption of graphene with wavelength stabilization

Abstract Quasi-bound states in the continuum (QBIC) has been demonstrated as an effective platform for enhancing light absorption in monolayer graphene. However, the absorption wavelengths of graphene metasurfaces typically shift as the asymmetry parameter is altered, and achieving robust graphene light absorption at a specific wavelength remains to be explored. Herein, we demonstrate that perfect absorption of graphene with wavelength stabilization can be realized by exciting the symmetry-protected QBIC (SP-QBIC) in metasurfaces with area compensation. Coupled mode theory enables reliable modeling of the absorption of the graphene metasurface with area compensation. The far-field multipole decomposition and near-field distribution reveal that the resonant absorption from the SP-QBIC is predominantly driven by the magnetic dipole mode. In addition, the absorption efficiency is robust to the variation of the structural parameters. The absorption intensity at the operating wavelength can be modulated by tuning the Fermi level of graphene or the azimuthal angle of the incident light. Our findings offer a route for the dynamic regulation of the absorption of graphene, facilitating the development of multifunctional switchers and absorbers based on QBIC.