Figure 3. Enhanced modal confinement of 1DSPPs.

Mode cross section of 1DSPPs as the cutoff condition is approached (blue-dashed K = 0 → red K = −0.87). Concentric contours, from the outermost to the innermost contour, correspond to (Ω^(R))⁻¹ = 0.6, 0.58, 0.56, 0.54, 0.52, 0.501, and 0.5002. The blue-dashed contour exactly coincides with that of the graphene bare edge plasmon (GEP). Each contour is defined as a line |E|² = constant enclosing an area A (in the xy plane), such that . Insets: (top) Mode cross section area A normalised to that of the GEP A₀ as a function of (Ω^(R))⁻¹ and (bottom) normalised intensity of the electric field (2 nm above the graphene) for the extreme cases (Ω^(R))⁻¹ = 0.6 (blue-dashed) and (Ω^(R))⁻¹ = 0.5002 (red). f = 50 THz; (Ω^(L))⁻¹ = 2.