基于时变声超构材料的非互易声学二极管

Nonreciprocal acoustic propagation and unidirectional acoustic isolation are of paramount importance in acoustic waves manipulation, and in perspective could revolutionise some key fields, such as underwater communication and medical ultrasound therapy, etc. At present, nonreciprocal acoustic waves manipulation is primarily underpinned by strong nonlinearity or magneto-acoustic effect.The practical application is severely hindered by low nonlinear conversion coefficiency, high power consumption as well as large volume. This project aims to explore and develop a highly integrated nonreciprocal unidirectional acoustic isolator with a superior performance, viz. acoustic diode.We propose to employ active time-varying acoustic metamaterials and study the related mechanisms of acoustic Doppler shift when the waves are propagating inside the time-varying metamaterials. By dynamically modulating the effective density or bulk modulus of metamaterials, we can realize an acoustic gauge potential,which bears much resemblance with a pseudomagnetic field. Theoretically, the designed acoustic gauge potential breaks the law of Lorentz reciprocity, and can be employed to construct acoustic isolators in a real sense.The project will attempt to carry out the experimental realization of time-varying acoustic metamaterials, and further build up the prototype of nonreciprocal unidirectional acoustic isolators with high transmission, low power consumption, and small fingerprint.

非互易声传播和单向声隔离对声能流控制具有十分重要的意义，更有望在水声通信和医学超声治疗等关键领域产生革命性影响。目前，非互易声调控主要通过强非线性或磁声效应来实现。其实际应用主要受限于低非线性转换效率，高能耗以及大体积。本课题旨在探索并发展一种集成度高且性能优越的非互易单向声导通器件，即声学二极管。拟采用有源时变声超构材料,研究声波在时变声超构材料中传播产生多普勒频移的相关机制。通过动态调制超构材料的等效密度或模量，实现一种类似磁势场的声学规范场。理论上，该声学规范场不满足洛伦兹互易原理，能在严格意义上实现声波单向隔离效果。通过项目支持，努力在实验上实现时变声超构材料，并构建出高透射率、低能耗以及小体积单向声隔离器件。

非互易声传播和单向声隔离对声能流控制具有十分重要的意义，更有望在水声通信和医学超声治疗等关键领域产生革命性影响。目前，非互易声调控主要通过强非线性或磁声效应来实现。其实际应用主要受限于低非线性转换效率，高能耗以及大体积。我们探索了一种集成度高且性能优越的非互易单向声导通器件，即声学二极管。采用有源时变声超构材料,发现声波在时变声超构材料中传播产生单向多普勒频移的相关机制。通过动态调制超构材料的等效密度或模量，可以构建一种类似磁势场的声学规范场。理论上，该声学规范场不满足洛伦兹互易原理，能在严格意义上实现声波单向隔离效果(正反透射比大于10000)。通过项目支持，在实验上实现声学拓扑绝缘体，并构建出高透射率(>80%)、低能耗(<20%)以及赝自旋关联的拓扑保护单向声隔离器件。