Fig. 5: The topological boundary state tuned by the Kerr nonlinearity.

a Band diagram of the topological waveguide for different input power. Distribution of the wave function for the b boundary mode, c left-hand edge mode, and d the right-hand edge mode. e Amplitude variation induced by the Kerr perturbation for v/w = 0.17 (Blue) and v/w = 0.7 (Magenta).