Tunable graphene quadrupole dark mode based ultranarrow Fano resonance in asymmetric hybrid metamaterial

We numerically demonstrate the ultranarrow high-order Fano resonance generated by the plasmonic coupling between graphene quadrupole dark mode and metallic bright magnetic dipole mode due to structural symmetry breaking effect in asymmetric hybrid metamaterials, consisting of periodic arrays of graphene nanoribbon and gold split-ring resonators. The graphene quadrupole Fano curve presents an ultranarrow lineshape with quality (Q) factor of 40. The proposed metamaterial shows the obvious dependence of the structural parameters and Fermi energy. Our designed asymmetric hybrid metamaterials shows a high sensitivity of 4.2μm/RIU and figure of merit (FOM) of 30, which could pave way for in label-free biomedical sensing.