Investigation of graphene-supported tunable asymmetric terahertz metamaterials

Abstract

By integrating a graphene layer with asymmetric split-ring metamaterial (MM) metal resonators, we investigated tunable propagation properties in the terahertz regime, including the effects of graphene Fermi levels, structural parameters, and operation frequencies. The results reveal that a sharp inductor-capacitor (LC) resonance can be observed at low frequency for the asymmetric MM structure, and its Q factor can reach more than 17.5. With the help of a graphene layer, the optical response is modulated efficiently. For instance, if the Fermi level changes in the range of 0.01–0.3 eV, for the semiconductor MM structure, the modulation depths (MDs) of amplitude and frequency are 27.0% and 43.4%, respectively. In addition, the resonant curves of indium antimonide (InSb) MMs can be modulated by changing the temperature; the amplitude MD is 56.2% as the temperature changes in the range of 350–800 K. The Q factor of the InSb MM structure is about 44.6. The results are helpful for designing novel graphene-based tunable terahertz devices, e.g., filters and modulators.