Supplement to: Phase Resolved Surface Plasmon Interferometry of Graphene

Here we provide further discussion of the details underlying the model calculations presented in Fig. 4 in the main text. The model describes the observed s-SNOM phase and amplitude from graphene Dirac plasmons in terms of the wavelength and damping as they depend on local Fermi energy and carrier mobility. Fig. S1 shows an expanded version of Fig. 4 in the main text, with a schematic of the cavity model (a). Eq. 2 of the main text describes the SPP response as: Ψgr = ψ̃gr + ψ̃SPP,0 +∑ i ψ̃SPP,i, (1)