Tunable terahertz band-stop filter using strongly coupled split ring resonators integrated with on-chip waveguide

We have used finite-element methods to design and simulate a tunable terahertz frequency range band-stop filter based on coupled split-ring resonators integrated into planar Goubau-line waveguide. Two split-ring resonators with different geometrical lengths and gap widths were designed to resonate at the same frequency. When the two resonators were coupled, resonance splitting was observed in the transmission spectra controlled by the distance between them. The electric field distribution and surface current modes in the coupled resonators were used to identify the origin of the resonance modes. In order to dynamically tune the coupled resonance frequencies, a cantilevered microelectromechanical scheme is proposed, in which the radius of curvature of one split-ring resonator is adjusted with respect to a fixed second split-ring resonator. The coupling strength of the coupled resonators was investigated as a function of the relative separation of the resonators revealing a dispersion relation that shows anti-crossing of the coupled resonances as the cantilever bends.