Fig. 2
From: Observation of nonlinear fractal higher order topological insulator
Topological solitons in fractal insulators. a Power vs propagation constant for the solitons bifurcating from the linear eigenstates concentrated around sites 1 (red curve) and 4 (blue curve) in the fractal array with r = 0.3a. Panels (c) and (d) show field modulus distributions corresponding to the dots in (a). b Power vs propagation constant for the solitons bifurcating from linear eigenstates concentrated around sites 1 (green, cyan and magenta curves) and 4 (orange curve) in fractal array with r = 0.6a. Field modulus distributions corresponding to the dots in (b) are shown in (e)–(h). In (a) and (b) gray regions are associated either with the eigenvalues of the localized states or with the bands of the delocalized states. i, j Power vs propagation constant for solitons in G4 fractal structure that correspond to the same types and locations of solutions as in panels (a),(b) that are for G3 fractal structure. Representative profiles of solitons in G4 structure are shown in Supporting Information
