Planar terahertz multi-resonator meta-waveguide based upon strongly coupled nested split-ring resonator

In this paper, we propose terahertz (THz) meta-waveguide geometry based on one-dimensional array of nested split-ring resonators (SRRs) comprising three split gaps. The meta-waveguide geometry consists of three layers of materials namely copper, dielectric and meta-molecules. The meta-molecules of aluminum with nested split gaps are placed periodically in one dimension along the wave propagation direction. The numerically obtained waveguide transmission spectrum shows the excitation of multiple resonances, resulting from three split gaps and a strong coupling between them. We found that the resonant frequencies of the guided modes can be tuned by varying the inter-split gaps separation which controls the coupling. The meta-waveguide geometry offers greater interaction of meta-molecules with the propagating terahertz radiation which can be sensitive to various applications. Further, the proposed design offers a flexibility in tuning resonant behavior owing to nested split gaps and coupling between them. We have examined the electric field distribution to confirm the multiple resonance excitations supported by the meta-waveguide geometry. We have also suggested a coupled harmonic oscillator model to interpret and analyze the numerically simulated waveguide transmission results. The study opens up new avenues for terahertz meta-waveguide based highly sensitive devices such as sensors, storage applications etc. where properties can be controlled via coupling within a resonator in a nested split gaps approach. © 2024 Elsevier GmbH