Fig. 3
From: Observation of nonlinear fractal higher order topological insulator
Observation of nonlinear states in fractal array with r = 0.3a. Output intensity distributions after 10 cm of propagation for the excitation of sites 1 (a), 2 (b), 3 (c) and 4 (d) in G3 fractal array. Figures with the maroon background show experimental results, while figures with the white background show results of theoretical simulations. Gray ellipses in all panels indicate waveguide locations. Input pulse energies E and powers U are indicated on each plot. All distributions are shown within the window − 23≤x, y≤23. Arrows in the experimental panels indicate position of the input excitation
