A planar metamaterial based on metallic rectangular-ring pair for narrow electromagnetically induced transparency-like effect

Abstract

We design numerically and demonstrate experimentally a planar metamaterial with a narrow band electromagnetically induced transparency (EIT)-like resonance at microwave frequencies. The meta-molecule, consisting of a pair of metallic rectangular rings connected by a top metallic strip, is mirror symmetric with respect to the exciting electric field of the normally incident wave. The coupling between a broad bright mode (electric dipole) of the whole meta-molecule and a sharp dark mode (electric quadrupole) belonging only to the rectangular-ring pair can efficiently induce an ultra-narrow EIT-like resonance. By using a coupled-resonator model that shows good accordance with the numerical and experimental results, the observed effect can be well explained. Our design provides another way to realize the sharp EIT-like behavior with strong dispersion and the slow-wave effect, which may find potential applications in constructing the slow-wave devices, filters, and sensors.