Tunable high Q-factor terahertz complementary graphene metamaterial

Based on the complementary graphene asymmetric double bars patterns, the tunable Fano resonances with large Q-factors have been investigated in the terahertz regime, including the effects of Fermi levels, structural parameters and operation frequency. The results reveal that compared with existed graphene tunable devices, the Fano resonant curve is very narrow and indicates a large Q-factor of about 60. The strong Fano resonant curves can be convenient tailored. As Fermi level increases, the amplitude of the Fano dip decreases, and the resonant peak position shifts to high frequency. The amplitude modulation depth (MD) of the Fano curve is more, about 90%, if the Fermi level changes in the scope of 0.2-1.0 eV. With the increase of the sample refractive index, the resonant Fano dip shifts low frequency, and the dip amplitude MD can reach more than 40%. The results are very helpful to understand the tunable mechanisms of graphene based Fano systems and to design high sensitivity functional devices, e.g. sensors, modulators, and antenna.