基于PT对称的声波超前/延迟线  

Acoustic advance/delay line based on PT symmetry

作　　者：张海啸 夏一宁 廖丹薇 刘昕昀 刘小利 张含 鲍彧 Haixiao Zhang;Yining Xia;Danwei Liao;Xinyun Liu;Xiaoli Liu;Han Zhang;Yu Bao(School of Electrical and Information Engineering,Changzhou Institute of Technology,Changzhou 213032,China;School of Physics,MOE Key Laboratory of Modern Acoustics,Nanjing University,Nanjing 210093,China;School of Microelectronics and Control Engineering,Changzhou University,Changzhou 213001,China)

机构地区：[1]常州工学院电气信息工程学院,常州213032 [2]南京大学物理学院,近代声学教育部重点实验室,南京210093 [3]常州大学微电子与控制工程学院,常州213001

出　　处：《科学通报》2024年第13期1794-1802,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(62001060,11904035);江苏省自然科学基金(BK20220616);江苏省高校“青蓝工程”优秀青年骨干教师项目;江苏省高等学校自然科学研究项目(23KJD140001,22KJB140001);常州市科技计划(CJ20220256)资助。

摘　　要：低损耗、长带宽、时间可控的声波延迟线在音频、射频、声表面波信号处理等领域具有非常广泛的应用,然而设计满足上述三点特性的声延迟线是一项极具挑战性的工作.近年来,量子力学中的宇称时间(parity-time,PT)对称概念被引入到声学系统中,其散射矩阵在特殊点处的实数本征值揭示了声波在此类系统中可实现宽带的无损传输,且传输相位可调.本文设计了一种由一对PT对称的导纳超表面及夹在中间的等效声学介质组成的声学系统,通过设置导纳超表面参数调节其工作机制,从而实现了两类互补的特殊点.其中防反射层模式下的特殊点导致了一种声波延迟线的形成,而相干完美吸收-激“声”模式下的特殊点则用于设计一种罕见的声波超前线.由于此声学损耗-增益超表面在自然界中是不存在的,本文利用可主动控制的电热声碳纳米管薄膜来模拟它.仿真结果表明,PT对称系统是实现低损耗、长带宽且时间可控的声波超前/延迟线的优良载体,其应用可扩展至包括光学、力学、弹性波等诸多波动领域.As a kind of essential acoustic engineering device,acoustic delay lines are widely used in the fields of audio,radio frequency and surface acoustic wave signal processing.Their main design goals include low insertion loss,wide operating bandwidth,and controllable delay time.In the audio band,topological acoustic delay lines designed using topological boundary states with no backscattering and defect immunity can solve the problem of low loss and time control,however the operating band is narrow and the device volume is excessive.In addition,recently reported slow optical effects in topological unidirectional waveguides also open the possibility of using slow acoustic effects for the design of acoustic delay lines.On the other hand,due to the causal law of real physical systems,acoustic advance lines with opposite effects to acoustic delay lines cannot be realized in passive systems.How to overcome such difficulties and successfully design acoustic advance lines is also a hot issue to be addressed in the study of acoustic time control devices.In this paper,we construct a PT-symmetric acoustic system consisting of a pair of loss and gain admittance metasurfaces and an intermediate acoustically equivalent medium,and tune its operation mechanism by setting the metasurface admittances such that two complementary scattered EP points are realized.The first is called the coherent perfect absorption-laser(CPA-Laser)mode,where the reflection coefficient of the system is 0 and the transmission coefficient is 1,indicating that the sound energy is transmitted lossless in the system,and the transmission phase is positive,so the system can be designed as the previously reported acoustic advance line.The second is the antireflections(ARCs)mode,in which the sound energy can be transmitted lossless,the transmission phase is negative,and the corresponding device is the acoustic delay line.We then use the carbon nanotube(CNT)films to fully model the acoustic admittance metasurfaces,and study the time-domain difference between the ou

关 键 词：PT对称声学 声学超表面 碳纳米管薄膜 声波超前/延迟线 

分 类 号：O429[理学—声学]