Terahertz Meta-waveguide Based upon Strongly Near-Field Coupled Split-Ring Resonators

In this article, we propose a terahertz meta-waveguide that exploits the near-field coupling between split-ring resonators (SRRs) and enables terahertz wave propagation in a waveguide configuration. One-dimensional array of coupled split-ring resonators are designed on a quartz substrate which is coated with metal on its back. The configuration allows the propagation of terahertz in a highly confined manner whose properties depend upon near-field coupling between resonators. We numerically examine terahertz waveguide transmission by varying the gap between two resonators (G) which controls the coupling between them. It is observed that the frequency of modes can be controlled when the gap between the resonators is varied. We also examine the effect of the split gap of a resonator (g) on waveguide transmission in the coupled configuration. It further gives an extra degree of freedom to control the waveguide transmission. Numerical findings have been analyzed and interpreted through a theoretical model based on coupled harmonic oscillators. The electric field profiles are also examined to understand the coupling behavior between the resonators. Finally, to understand the guided mode properties and confinement, we calculated the full width at half maxima (FWHM) of the propagating mode at different locations of the meta-waveguide along the propagation direction. The meta-waveguide designs using near-field coupling between resonators can provide a more flexible approach to control the propagation and hence design terahertz-guided wave devices and components.