Slow light for a graphene-based metamaterial with a dual plasmonic-induced transparency effect

This study proposes a tunable metamaterial device based on a graphene-silicon dielectric composite structure. The three layers of graphene with different lengths in the device act as bright and dark modes, respectively. When the bright and dark modes interact, a significant dual plasmonic-induced transparency effect is formed. Through systematic theoretical modeling and numerical simulation, a complete theoretical analysis framework is established based on the coupled-mode theory, which deeply reveals the interaction mechanism between bright and dark modes. This device achieves a significant slow-light effect with a maximum group refractive index of 481.07. Additionally, as the Fermi level increases, the group refractive index of the PIT windows significantly increases, and the resonant frequency also shows a blue-shift phenomenon. These outstanding performances endow this structure with important application values in terahertz communication, slow-light regulation, high-sensitivity biosensing, reconfigurable optical storage, and other fields.