(a) A GSR resonator with diameter D, width W and gap distance g. (b) The normal-incidence transmittance (blue) and absorbance (red) spectra of a square split-ring array on monolayer graphene (solid curves) and monolayer gold (dotted curves). The geometrical parameters of the metamaterial array are W=g=D/10 with D=1 µm for graphene and D=8.19 µm for gold. According to Equation (7), the parameters yield resonance values within the same frequency range. The lattice spacing is 2D for both cases. Graphene is described by a Drude model with a Fermi energy of EF=0.5 eV and a damping constant of γ=1 meV. Gold is described by its bulk parameters, assuming a thickness equal to the distance between the (111) atomic planes (t=0.29 nm). The incident-field polarization is across the gap (y direction). GSR, graphene split-ring.