Dynamically tunable terahertz slow light device based on triple plasmonic induced transparency

A simple graphene-based device with excellent performance is proposed. This device can realize a terahertz triple dynamically tunable plasmonic induced transparency effect. The optics slow light application is also investigated in detail. The functional structural unit of this device is double graphene layer and silicon-air grating. Under the auxiliary excitation of periodic silicon-air grating, the electrons in the lower graphene layer can be perfectly excited by incident energy, so it can be considered as a bright mode and can be easily detected. The electrons in the upper graphene layer respond very slowly or even have no response to incident energy, so it is considered as a dark mode. When the resonant frequencies of bright and dark modes are the same or close, interference phase effect can occur, thus forming a triple plasmonic induced transparency effect. Furthermore, the double graphene layer in this proposed device is in a continuous state rather than discontinuous state, thus it is very convenient to regulate the carriers of graphene through external voltage, thereby achieving a tuning performance of the device. The Fermi level of graphene can also be adjusted externally under the external voltage. The slow light performance of this proposed device is also researched in this paper. The group delay and group refractive index achieved by this structure can reach up to 0.304 ps and 607.6, respectively. This investigation is expected to provide a potential theoretical basis for slow light, sensing, optical storage, and other aspects.