Multidimensional Rainbow Trapping of Sound in the Second‐Order Topological Sonic Crystals

Topological rainbow trapping, which can separate and trap different frequencies of topological states into different positions, plays a key role in topological acoustic devices. However, few schemes have been proposed to realize multidimensional topological rainbow trapping effects with the hierarchy of edge and corner, which has partly restricted their practical applications in multifunctional integrated acoustic devices. Herein, a tactic to realize a multidimensional topological rainbow trapping of acoustic wave with the hierarchy of edge and corner in the second‐order topological sonic crystals is proposed. Based on the designing of a self‐ordering structure to both induce the topological phases of the bulk and edge states in the rectangular lattice, the edge states and corner states are obtained. Furthermore, the regularity between the located frequency of topological edge and corner states and the geometric parameters are discussed in detail. Finally, the rainbow trapping effects for topological edge states and corner states are investigated, respectively, in which different frequencies of topological acoustic edge and corner states are well separated and trapped in different positions without overlap. This proposal may provide a novel way for multidimensional wave manipulation and the integration of multifunctional acoustic devices.