The Influence of Element Deformation on Terahertz Mode Interaction in Split-Ring Resonator-Based Meta-Atoms

The interaction between terahertz (THz) resonance modes and element deformation in rectangular split-ring resonator (RSRR)-based meta-atoms (MAs) is investigated experimentally. Two types of RSRR-based MAs are presented: lateral-varied SRR (LV-SRR) and arm-twisted SRR (AT-SRR). When the distances from the gaps to the opposite sides of above meta-atoms increase from 10 to 40 μm, the inductive-capacitive (LC) resonance modes and dipole oscillation modes exhibit redshift behavior. The quality factor (Q factor) of LC resonance decreases while that of dipole oscillation modes increases. The THz mode interaction is subject to the distance between the gap and opposite side. An extension of lateral side contributes much more to the enhancement of Q factor of dipole oscillation mode than the twisted arms. The relationship between the near-field coupling effect and THz modes is revealed by the analysis of surface currents as well as the electric energy density distribution, as is in agreement with the experimental results.