Dispersions and field distributions of the modes for the free-standing graphene monolayer and the type-I band of the graphene–hBN heterostructure. The dispersions for (a) graphene (E_F = 0.5 eV), (c) hBN and (e) their hybrid structure. (b), (d), (f). The field profiles of the modes of graphene, hBN and their hybrid structure at ω = 1700 cm⁻¹, 800 cm⁻¹, and 800 cm⁻¹, respectively. The corresponding frequency positions in the left dispersion figures are indicated by red dots. The black lines in the field patterns profile the hyperbolic layer and the red line indicating the graphene sheet.