Valley topology in non-Hermitian elastic hexangular lattice structure with ABH edges

The valley topology concept provides new methods for wave manipulation, and structures consisting of gain or loss elements can be used to simulate the properties in non-Hermitian structures. In this paper, the existence of the valley topologically protected edge in non-Hermitian structures with the PT symmetry broken is demonstrated both in theory and numerical simulation. The proposed structure comprises the unit cell with acoustic black hole (ABH) edges, which provide a broad band gap for wave propagation manipulation. First, the detailed description of the unit cell is analyzed. Subsequently, the properties of wave propagation in non-Hermitian structures are numerically calculated and discussed. The investigation provides a new potential method to introduce valley topology design in elastic non-Hermitian structures for elastic wave regulation.