Plasma modes in periodic two-dimensional superconducting-wire networks

We have investigated plasma modes in thin niobium superconducting wire networks deposited onto a ${\mathrm{SrTiO}}_3$ substrate and find that their frequency is strongly lowered in comparison to homogeneous films. The dispersion relations present a crossover from a thin film regime (two dimensional) to a wire regime (one dimensional). Surprisingly it occurs at a very long wavelength that is nearly sixty times larger than the array period. A model based on interacting independent parallel wires is proposed to understand this crossover.