Tunable high-performance optical switch via quasi-bound states in the continuum controlled by graphene Fermi energy

Through controlled breaking of the symmetry of the system, multiple bound states in the continuum (BICs) are transformed into quasi-BICs (QBICs), generating high quality factor resonance peaks. These peaks can be used to generate optical switches, thereby enhancing both the quantity and modulation depth of optical switches. We propose a bilayer graphene sandwich dielectric corrugated structure to realize an optical switch. The spectral positions of the transmission and reflection resonance peaks can be tuned via modulation of graphene of Fermi energy. When the Fermi energy is 1 eV or 0.2 eV, the ON or OFF state of the optical switch can be selected. The modulation depths of all transmission and reflection are close to 100% and are mainly supported by the electric quadrupole (EQ) component. Our research provides a feasible way to design excellent applications based on QBIC in tunable optical switches.