Figure 4. The schematic and dispersion curves of fundamental mode for double-layer structure.

(a) Schematic of the circular cylindrical double-layer graphene structure with dielectric loading, the radius of the dielectric medium is r_a, the dielectric film is in the region r_a < r < r_b, the radius of trajectory projection of CEB is r₀. (b) The dispersion curves of fundamental mode, the parameters are r_a = 3 μm, r_b = 4 μm, ε₁ = 12, and ε₂ = 2, the inset is the Fourier spectrum of radiation field E_z.