Transmission characteristic of asymmetric double-split ring resonator in terahertz wavelength

An asymmetric planar terahertz metamaterial (MM), composed of two different single split-ring resonator (SRR), was designed and fabricated. Its transmission performance was obtained through numerical simulation and experiment. The simulations revealed that, under the case of perpendicular polarization, two transmission dips occurred at the lower frequencies 0.540 THz and 0.925 THz, which were attributed to the inductor-capacitor (LC) resonances of the left and right rings respectively. At these two frequencies, the surface current and electric field mainly concentrated around the gaps of the two rings. At the higher frequency 1.885 THz, there was another transmission dip which originated from the dipole resonance of the sample. At this time, the surface current had two opposite circulation directions, and besides, the electric field and surface current were distributed throughout the sample. However, the two lower-frequency LC resonances would be absent when the polarization direction of incident terahertz waves was rotated 90. The experiment results coincide well with the numerical simulations. This metamaterial structure was expected to provide important reference for the design of terahertz modulator, filters, absorbers and polarizers.