Self-localized topological states in three dimensions

Abstract

Three-dimensional (3D) topological materials exhibit much richer phenomena than their lower-dimensional counterparts. Here we propose self-localized topological states (i.e. topological solitons) in a 3D nonlinear photonic Chern insulator. Despite being in the bulk and self-localized in all 3D, the topological solitons at highsymmetry points K and K rotate in the same direction, due to the underlying topology. Specifically, under the saturable nonlinearity the solitons are stable over a broad frequency range. Our results highlight how topology and nonlinearity interact with each other and can be extended to other 3D topological systems.