Manipulating the resonant behaviors in the asymmetric terahertz metamaterials

We experimentally and numerically demonstrate that resonant behaviors of asymmetric terahertz metamaterials can be excited and tuned by altering the position of the intermediate wire. For the parallel polarization of the terahertz E-field to the bottom bar, we attribute the low frequency to the superposition of two inductive-capacitive circular currents, which are generated by the shared intermediate wire and lateral arms. In perpendicular polarization, the observed low-frequency resonance modes are from coupling effect between the bottom bar and the vertical shortest arm under the broken symmetry of the structures. Our asymmetric structures offer the potential applications in terahertz frequency selectors and filters.