Recently, there has been significant research interest in higher-order topological states within artificial lattices, primarily due to their potential for manipulating waves. In this study, we focus on a three-dimensi...Recently, there has been significant research interest in higher-order topological states within artificial lattices, primarily due to their potential for manipulating waves. In this study, we focus on a three-dimensional hexagonal bilayer acoustic crystal with rotation, layer, and translation degrees of freedom. By systematically reducing the crystal symmetries, we realize a full hierarchical structure of the higher-order topological states. This hierarchical progression begins with the valley-induced twodimensional surface state, followed by the one-dimensional hinge state that arises from the topological obstruction, and ultimately culminating in the zero-dimensional corner state resulting from the edge polarization mechanism. Through finite element simulations and numerical calculations of topological invariants, we confirm the topological origins of all these hierarchical states. Moreover, we successfully verified the full hierarchical topology by directly probing the acoustic field within a finitesized three-dimensional sample. This study offers novel perspectives on the fundamental research pertaining to wave modulation and the intelligent control of sound fields.展开更多
基金This work was supported by the Key-Area Research and Development Program of Guangdong Province(2020B010190002)the National Natural Science Foundation of China(11890701,11874383,12104480,11974005,and 12222405)+1 种基金the National Key R&D Program of China(2018YFA0305800)the IACAS Frontier Exploration Project(QYTS202110).
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grant No.2020B010190002)the National Natural Science Foundation of China(Grant No.12104480)the IACAS Frontier Exploration Project(Grant No.QYTS202110)。
文摘Recently, there has been significant research interest in higher-order topological states within artificial lattices, primarily due to their potential for manipulating waves. In this study, we focus on a three-dimensional hexagonal bilayer acoustic crystal with rotation, layer, and translation degrees of freedom. By systematically reducing the crystal symmetries, we realize a full hierarchical structure of the higher-order topological states. This hierarchical progression begins with the valley-induced twodimensional surface state, followed by the one-dimensional hinge state that arises from the topological obstruction, and ultimately culminating in the zero-dimensional corner state resulting from the edge polarization mechanism. Through finite element simulations and numerical calculations of topological invariants, we confirm the topological origins of all these hierarchical states. Moreover, we successfully verified the full hierarchical topology by directly probing the acoustic field within a finitesized three-dimensional sample. This study offers novel perspectives on the fundamental research pertaining to wave modulation and the intelligent control of sound fields.
