VALLEY HALL EDGE SOLITONS IN THE KAGOME PHOTONIC LATTICE

After more than 10 years in development, the nonlinear topological photonics is emerging as a new branch of physics. One of the most interesting subjects in the nonlinear topological photonics are the topological edge solitons. These solitary structures move along the edges of photonic crystals with constant speed, are immune to disorders/defects along the way, and maintain their profiles unchanged during long-distance propagation. In this paper, we present bright and dark valley Hall edge solitons in the kagome photonic lattice. These solitons emerge at domain walls that exist between different types of kagome lattices. We are interested in the wall between two specific types: the squeezed and expanded kagome photonic lattices. The solitons move along the wall without change in their profiles, thanks to the self-action effect of nonlinearity, and can circumvent sharp corners, thanks to the topological protection. Advances achieved in this paper represent new progress in the nonlinear topological photonics and may lead to applications in the development of novel photonic chips.