Resonance tuning behavior in closely spaced inhomogeneous bilayer metamaterials

We have measured the interaction between closely spaced bilayer split ring resonators (SRRs) by varying separation layer and orientation. Terahertz time domain measurements match closely to simulations for arrays separated by a thin micron-scale polyimide layer. Experimental results indicate that bilayer SRRs resonances strongly depend on interlayer coupling tunable by separation and orientation. Simulation shows a relatively high Q resonance (Q≈30) is associated with the "antialigned" SRR pair at separations of λ/500. Metamaterials tuned through interlayer coupling allows resonances at frequencies lower than the natural resonance of individual SRRs which has implications for electrically small antenna design.