A Graphene-Based Hybrid Plasmonic Waveguide With Ultra-Deep Subwavelength Confinement

Reduction of propagation loss of terahertz graphene plasmon can be made by increasing the chemical potential of graphene layer, but at the cost of significantly increased modal area, which fundamentally limits the packing density on a chip. By utilizing the strong coupling between the dielectric waveguide and plasmonic modes, we propose hybrid plasmonic terahertz waveguides that not only significantly suppress the mode field confinement, but also maintain a compact modal size. A typical propagation length is 127 μm, and optical field is confined into an ultra-small area of approximately 32.6 μm² at 3 THz. This structure also exhibits ultra-low crosstalk, which shows great promise for constructing various functional devices in future terahertz integrated circuits.