Fig. 3
From: Topological non-Hermitian origin of surface Maxwell waves
Phase diagrams of surface Maxwell waves. a Zones of the existence of zero, one, and two surface zero-helicity modes described by the topological helicity winding number Eq. (3) and the bulk-boundary correspondences Eqs. (4) and (5), see Fig. 2b. b Phase separation of the transverse-electric (TE) and transverse-magnetic (TM) modes described by the polarization indices Eq. (8). c The phase diagrams resulting from the combination of a and b. The two-mode quadrant (εr < 0,μr < 0) has both TE and TM modes in every point, but only one of these is propagating (i.e., having real wavevector \(k_{{\mathrm{surf}}}\)), while the other one is evanescent (having imaginary ksurf). d Splitting the phase diagram (c) with real ksurf into zones with real (bright areas) and imaginary (dark areas) frequency \(\omega _{{\mathrm{surf}}}\). These zones swap upon the inversion of the sign of the squared refractive index of the first medium, \(n_1^2 = \varepsilon _1\mu _1\)
