Tunable terahertz left-handed metamaterial based on multi-layer graphene-dielectric composite

A terahertz fishnet metamaterial, consisting of a gallium arsenide substrate sandwiched between multi-layer graphene-dielectric composites, is theoretically studied. Detailed analysis shows that this metamaterial has a left-handed transmission peak accompanied with an abnormal phase dispersion and a clear negative refractive index which originates from simultaneous magnetic and electric resonances. Our structure is unique because it has no metallic parts to achieve the left-handed properties. The most important utility of this metamaterial comes from the fact that its left-handed features can be dynamically controlled by applying external bias to shift the Fermi level in graphene.