We present frequency tunable metamaterial designs at terahertz (THz) frequencies using broadside coupled split-ring resonator (BC-SRR) arrays. Frequency tuning, arising from changes in near-field coupling, is obtained by in-plane displacement of the two SRR layers. For electrical excitation, the resonance frequency continuously redshifts as a function of displacement. The maximum frequency shift occurs for vertical displacement of half a unit cell, resulting in a shift of 663 GHz (51% of f(0)). We discuss the difference in the BC-SRR response for electrical excitation in comparison to magnetic excitation in terms of hybridization arising from inductive and capacitive coupling.
Ekmekci, E., Strikwerda, AC., Fan, K., Keiser, G., Zhang, X., Turhan-Sayan, G., & Averitt, RD. (2011). Frequency tunable terahertz metamaterials using broadside coupled split-ring resonators. Pysical Review B, 83(19), 193103. https://doi.org/10.1103/PhysRevB.83.193103