Fang Hang, Xie Guohuan, Huang Hongbo, Chen Jiujiu
College of Mechanical and Intelligent Manufacturing, Central South University of Forestry and Technology, Changsha, 410004, People's Republic of China.
State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082, People's Republic of China.
Sci Rep. 2024 Jul 24;14(1):17011. doi: 10.1038/s41598-024-67985-9.
Rainbow trapping, observed in elastic waves, has attracted considerable scientific interest owing to its potential applications in energy harvesting, buffering, and wavelength-division multiplexing devices. However, previous approaches have often necessitated complex geometric modifications to the scatterer, such as altering dimensions or shifting along diagonals to corners, limiting practical utility. Here, we realize the coupled topological edge states (CTESs) of elastic waves in a two-dimensional (2D) solid phononic crystal (PC) with inversion center changes. Changing the inversion center along the x or y directions by a specific distance can induce the topological phase transition. The topological edge states (TESs) arise at the interface by combining PCs with different topologies positioned adjacent to each other. Furthermore, it is demonstrated that TES exhibits topological robustness against defects. By introducing a gradient into the PC structure by altering the geometrical parameters of scatterers along the interface, the topological rainbow trapping of elastic waves is achieved. Finally, the CTES are generated by the interaction between TESs of different interfaces, which can lead to coupled topological rainbow trapping in phononic heterostructures with different displacement parameters along the multiple interface gradient. Our results pave the way for manipulating the symmetric and antisymmetric topological modes of elastic waves in topologically coupled waveguides, which offers potential applications in selective filtering and multiband waveguiding.
在弹性波中观察到的彩虹俘获现象，因其在能量收集、缓冲和波分复用器件中的潜在应用而引起了相当大的科学兴趣。然而，以前的方法通常需要对散射体进行复杂的几何修改，例如改变尺寸或沿对角线移动到角落，这限制了其实际应用。在此，我们通过改变二维（2D）固体声子晶体（PC）的反演中心来实现弹性波的耦合拓扑边缘态（CTESs）。沿x或y方向将反演中心改变特定距离可诱导拓扑相变。通过将具有不同拓扑结构的PC彼此相邻放置，在界面处产生拓扑边缘态（TESs）。此外，还证明了TES对缺陷具有拓扑鲁棒性。通过沿界面改变散射体的几何参数在PC结构中引入梯度，实现了弹性波的拓扑彩虹俘获。最后，CTES由不同界面的TES之间的相互作用产生，这可导致沿多界面梯度具有不同位移参数的声子异质结构中的耦合拓扑彩虹俘获。我们的结果为在拓扑耦合波导中操纵弹性波的对称和反对称拓扑模式铺平了道路，这在选择性滤波和多波段波导方面具有潜在应用。
