Ultra-compact, low-loss terahertz waveguide based on graphene plasmonic technology

In order to meet the demand for highly integrated terahertz chips with ultra-low transmission loss, a novel hybrid graphene plasmonic waveguide is proposed, wherein low-index insulators are embedded between a slot-rib (covered by graphene) structure and a high-index dielectric waveguide. This designed waveguide combines the plasmonic response of graphene, energy distribution mechanism of materials with large refractive index difference, and modal properties of hybrid plasmonic waveguide to yield superior waveguiding performance. We achieved 50 times stronger mode confinement along with five times smaller propagation loss, as compared to the traditional graphene hybrid plasmonic waveguide operating at 3 THz. Investigation on the influence of modal properties on chemical potential of graphene revealed an active approach to control mode confinement or propagation distance. In addition, owing to the ultra-strong energy confinement of modes, the crosstalk caused by coupling between two parallel waveguides is negligible, which paves the way for realizing ultra-compact, chip-level terahertz devices.