一维合成维度水基声子晶体  

One-dimensional synthetic waterborne phononic crystals

作　　者：胡晨阳 梁家洛 郑日翌 陆久阳 邓伟胤 黄学勤 刘正猷[2] Hu Chen-Yang;Liang Jia-Luo;Zheng Ri-Yi;Lu Jiu-Yang;Deng Wei-Yin;Huang Xue-Qin;Liu Zheng-You(School of Physics and Optoelectronics,South China University of Technology,Guangzhou 510640,China;Key Laboratory of Artificial Micro-and Nanostructures of Ministry of Education,School of Physics and Technology,Wuhan University,Wuhan 430072,China)

机构地区：[1]华南理工大学物理与光电学院,广州510640 [2]武汉大学物理科学与技术学院,人工微纳结构教育部重点实验室,武汉430072

出　　处：《物理学报》2024年第10期221-226,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12074128,12222405);广东省自然科学基金(批准号:2021B1515020086,2022B1515020102)资助的课题。

摘　　要：水下声学在水下通信、水下定位和导航等方面具有广泛的应用.借助拓扑物理的概念,研究水基声子晶体中的拓扑态为水下声波的创新性调控提供了一种全新的手段,既有基础研究价值,又有重要的应用前景.本文设计了一种一维的双层铁栅水基声子晶体,通过把层间的相对横向平移量等效成一个合成维度,实现了合成二维狄拉克点.相对平移量的改变导致二重简并能带打开带隙.伴随着带隙的打开、闭合以及再次打开,能带发生翻转,也就是发生拓扑相变,从一种能谷相变化到另一种能谷相.在不同能谷相声子晶体构成的界面处,能谷陈数保证界面态的确定性存在.数值仿真与实验测量结果吻合良好,都展示了不同能谷相声子晶体的体能带以及它们之间的界面态色散.本文提出的水基声子晶体结构简单,借助合成维度的概念,为在低维实空间体系中研究高维体系拓扑特性提供了一种有效的途经,有望为拓扑功能性水声器件的设计提供新思路.此外,可以把实空间体系拓展到二维甚至是三维,并引入更多的合成维度,用于研究更高维度体系的拓扑态及其输运特性.Underwater acoustics has wide applications in underwater communication,underwater positioning,underwater navigation,and so on.Inspired by the concept of topological physics,the study of topological states in waterborne phononic crystals provides a brand-new way for innovatively controlling underwater waves,which has both basic research value and important application prospects.In this work,we design a one-dimensional bilayer iron grid waterborne phononic crystal to realize a synthetic two-dimensional Dirac point by considering the relative lateral translation between the two layers as a synthetic dimension.Through changing the relative lateral translation,the double degenerate band opens a gap,which is characterized by the valley Chern number.As the band gap opens,closes and reopens,the bulk band undergoes a band inversion,that is,a topological phase transition from one valley topological phase to another.At the interface formed by two phononic crystals with distinct valley topological phases,the valley Chen number ensures the deterministic existence of the interface state.Experimental measurements are in good agreement with numerical simulations,both showing the bulk bands of waterborne phononic crystals at different valley topological phases and the interface state dispersion between them.The waterborne phononic crystal proposed in this work has a simple structure.With the help of the concept of synthetic dimension,it provides an effective way to study the topological properties of high-dimensional systems in low-dimensional real space systems,and gives new ideas for designing topological functional underwater acoustic devices.In addition,we can expand the real space system to two or even three dimensions,and introduce more synthetic dimensions to study the topological states and associated transport characteristics of higher-dimensional systems.

关 键 词：水基声子晶体 合成维度 狄拉克点 界面态 

分 类 号：O735[理学—晶体学]