Plasmon-Induced Transparency and Dispersionless Slow Light in a Novel Metamaterial

We propose a novel metamaterial structure to realize dispersionless slow light based on plasmon-induced transparency (PIT) at optical frequency. Simply by breaking the symmetry of the metamaterial structure, two electric excitation coupling to the magnetic resonance (EEMR) modes generate and interplay with each other resulting the formation of the PIT resonance. Due to the hybridization of the two EEMR modes, an ultrabroad flat-band as large as 15 THz with average group index of $\sim 5$ is obtained. The corresponding normalized delay-bandwidth product is 0.475, which indicates the prominent feature in light slowing down without distortion. The proposed metamaterial structure is promising for practical information storage, optical memory, and optical buffers design.