Fig. 1. (a) 3D schematic diagram composed of graphene gratings and graphene sheets; (b) 2D side view of the proposed system; the specific parameters are as follows: P=490  nm, w=400  nm, h1=12  nm, h2=1350  nm, h3=100  nm, Ef′=Ef=1.0  eV.

Fig. 2. (a) Absorption spectra of the proposed system; (b)–(f) electric field distribution of different modes in the y direction.

Fig. 3. BIC formation in the hybrid FPR–GMR system. (a) Absorption spectrum as a function of the width of the graphene grating; (b) cross sections of the absorption spectra at w=168 nm and 144 nm show the appearance of the collapsed F–W BIC to quasi-BIC. (c) Avoided crossing and linewidth vanishing due to the coupling of FPR and GMR modes at different w.

Fig. 4. (a) Schematic diagram of CMT; (b) coupled absorption spectra of FDTD numerical simulation and CMT fitting at w=400  nm.

Fig. 5. (a) Band structures of the proposed FPR–GMR hybrid system. Here, the illustration shows electric field distribution at F-W BIC. (b) Simulated Q-factor evolution for the GMR band.

Fig. 6. (a) F–W BIC dynamically modulated by the Fermi energy level of a graphene grating (w=144  nm); (b)–(e) field distribution of the two modes in the y direction when Ef′=1.0  eV and 0.3 eV; (f) perfect absorption frequency modulator and optical switch based on F–W BIC.