Superconductive Ultracompact Magnetically Coupled Resonator With Twin-Spiral Structure

We describe a practical design of an ultracompact on-chip superconductive microresonator as a potential magnetic element of metamaterial. The achieved resonator size with respect to the wavelength in our experiment is about λ/14 400. The resonator consists of two superconducting Nb spirals, sandwiched face to face, with a small gap filled with dielectric. The spirals are turning in opposite directions: one clockwise, another counterclockwise. We study the resonator spectral response and its inner modes using numerical simulation in HFSS. In experiment with a laser scanning microscope, we confirm the predictions for the resonance frequencies of Nb superconductive resonator and its inner modes structures. Small size and the ease of manufacturing make the two-spiral resonator an attractive solution for superconductive filters, coupling circuits, and as a magnetic component of a metamaterial.