Higher-order topological insulators have attracted significant attention in the classical wave manipulation field because of their ability to host lower-dimensional topological protected states. The introduction of the valley degree of freedom confers the typical valley-selective excitation characteristic on higher-order topological corner states. However, in valley phononic crystals, the effect of corner structure types on the excitation characteristics of corner states has not been widely discussed or investigated. In this work, we realize multiple distinct corner-dependent excitation characteristics of higher-order topological corner states in the same bulk band gap based on two-dimensional valley phononic crystals. We propose a valley phononic crystal based on a plate trimer, achieving corner states with tunability and valley-switchable excitation characteristics. Further, we design a multicorner superstructure containing various intersection angles. Within this system, we achieve the two typical excitation characteristics supported by traditional corner structures with valley selectivity and valley switching capability. Interestingly, we find that certain specific corner structures simultaneously support the excitation of both corner states with distinct valleys, with no need to rotate the scatterers. And our study confirms that the corner states enable reconfigurability and exhibit robustness against defects and disorders. This study enhances the spatial multiplexing capability and structural design flexibility of higher-order topological corner states, laying the foundation for the development of programmable topological functional devices in phononic systems.

Close

PrevNext

View figure in article

• Symmetry protected topological states
• Topological effects in acoustic systems
• Topological insulators
• Valley degrees of freedom
• Topological materials
• Triangular lattice