Observation of Floquet solitons in a topological bandgap

Abstract

Topological insulators go nonlinear Whereas solid-state insulators tend to be fixed by material properties, photonic topological insulators can be designed at will to mimic a variety of scenarios and complex interactions. Mukherjee and Rechtsman go beyond the linear optical regime that has been studied to date and show that photonic topological insulators can also exhibit nonlinear optical features (see the Perspective by Ablowitz and Cole). Their array of laser-written waveguides can support solitons, which are also found to exhibit topological features, performing cyclotron-like orbits associated with the topology of the lattice. The nonlinear properties provide a rich playground for further exploration, with the possibility of mimicking other interacting bosonic systems. Science , this issue p. 856 ; see also p. 821