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

Abstract

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 μm 2 at 3 THz. This structure also exhibits ultra-low crosstalk, which shows great promise for constructing various functional devices in future terahertz integrated circuits.

Reconfigurable THz Plasmonic Antenna Based on Few-Layer Graphene with High Radiation Efficiency

“…Although there is not a definitive consensus on the definition of FLG, most works consider it to be graphene sheets with no more than five layers [9,13,14]. The optical conductivity of FLG is $N{\sigma }_G$ [13], where ${\sigma }_G$ is the surface conductivity of MLG calculated by the Kubo formula [15] and N is the number of layers.…”

“…The layer thickness of both Al 2 O 3 and PMMA are assumed 100 nm, well within fabrication limits [12], whereas the excitation frequency is 3 THz. Intuitively, antennas based on GS could provide higher efficiency through mode coupling and higher miniaturization due to their field confinement potential as sought in waveguide designs [9]. …”

“…Other configurations such as few-layer graphene or certain graphene stacks would theoretically lead to higher radiation efficiency thanks to their higher conductivity and mode coupling, respectively. However, few-layer graphene has been considered for plasmonic waveguides with high confinement [9] and for antennas as an auxiliary element [10], but not as the radiating element of plasmonic antennas; whereas graphene stacks have been introduced in [11,12] seeking self-biased reconfigurability, not better radiation efficiency.…”

Terahertz Dielectric Resonator Antenna Coupled to Graphene Plasmonic Dipole

“…Therefore, the 1D structure is PMMA-Graphene-PMMA-GaAs-air. Note that the absorption losses of GaAs and PMMA are not included in the following analysis since they are small as opposed to that of graphene in the THz frequencies [15]. Wave is assumed to propagate in the x-direction and to be invariant in the y-direction.…”

Tunable Plasmonic Filter Based on Graphene Split-Ring

“…Despite the large wavevector mismatch between GPs and free-space photons, several methods have been devised to excite GPs efficiently, such as grating coupling [10,11] and tapered polaritonic slab waveguide [12]. By using randomly stacked multilayer graphene, the wavevector of GPs can be substantially reduced as well [13,14]. Resonator-waveguidecoupled system is a generic configuration in photonics devices which is widely used in the field of filtering, switching, and sensing.…”