基于非共振单元的声学超构介质构建、效应及应用

Limited to the high transmission loss and narrow working bandwidth, sound manipulation through acoustic meta-materials constructed by traditional locally-resonant elements can not fulfill the new application requirements. It is important to introduce non-resonant elements into acoustic meta-materials, construct their model, discover the inside physical effects, and develop new functional devices. Recent studies have shown that the array of non-resonant elements based on coiling-up space can be regarded as acoustic meta-materials with extreme effective parameters. However, due to the structural complexity of the elements, the relationship between the key parameters of the elements and the macroscopic manipulation properties is not clear. In addition, the mechanism of negative/zero effective parameters is not clarified. In this proposed project, we will make the theory analysis, computer simulation and experiments to give systematic and thorough research on acoustic meta-materials based on non-resonant elements. First, we will quantify the influence on the effective parameters by the structural characters, coiling-up factors and arrangement pattern of the non-resonant elements. Physical model of non-resonant acoustic meta-materials with low transmission loss and wide working bandwidth will be established. Furthermore, new physical effects such as the generation of negative/zero effective parameters, backward phase-matching and second-harmonic generation will be characterized and designed. On this basis, we will develop new acoustic functional devices according to the novel manipulation effects. This research will be helpful to discover new effects of acoustic waves and broaden the design concept of novel acoustic functional devices.

由于耗散大、带宽窄等性能局限，传统的局域共振单元声学超构介质已无法满足声场调控设计需求。如何将非共振单元引入超构介质的设计中，构建其物理模型、探索其中新的物理效应并应用于新原理功能器件，正成为声学人工材料领域的研究重点。近期研究表明，折叠空间非共振单元阵列可等效为有效折射率特异的声学超构介质。但是，由于单元本身的复杂性，结构参数与调控性质的关系尚不清楚，基于相位延迟调制的负/零有效系数形成机理也未澄清。本项目将从理论分析、数值模拟和实验验证等不同层次，对非共振单元超构介质进行系统深入的探索：首先分析单元的几何特征、折叠倍数、排列方式等对等效参数的影响，构建低损耗、宽频带的非共振超构介质物理模型；进而对其负/零有效系数产生演化、后向波相位匹配、二次谐波激发等新效应进行表征与设计；在此基础上，应用特异调控性能构建声波功能器件。本项目有助于发现新的声波效应，开发新型功能器件，具有重要的应用前景。

由于耗散大、带宽窄等性能局限，传统的局域共振单元声学超构介质已无法满足声场调控设计需求。如何将非共振单元引入超构介质的设计中，构建其物理模型、探索其中新的物理效应并应用于新原理功能器件，正成为声学人工材料领域的研究重点。近期研究表明，折叠空间非共振单元阵列可等效为有效折射率特异的声学超构介。但是，由于单元本身的复杂性，结构参数与调控性质的关系尚不清楚，基于相位延迟调制的负/零有效系数形成机理也未澄清。本项目从理论分析、数值模拟和实验验证等不同层次，对非共振单元超构介质进行了系统深入的探索：首先分析了单元的几何特征、折叠倍数、排列方式等对等效参数的影响，构建了低损耗、宽频带的非共振超构介质物理模型，取得的代表性成果包括提出了在无背景流速的超材料声子晶体中构造声学赝自旋偶极子和四极子模式、并实现声波拓扑传输的理论方法；进而对其负/零有效系数产生演化、后向波相位匹配、二次谐波激发等新效应进行了表征与设计；在此基础上，应用特异调控性能构建了一系列声波功能器件，例如将声波类量子效应与声学新原理功能器件相结合，获得了拓扑保护声单向传输、可重构声学路径选择开关、声拓扑延迟线、声学定向天线等一系列新颖的声场调控功能，另外基于偶极子薄膜网络阵列，首次设计出一种简单高效的、具备近零有效密度的声学超构材料，可以产生无散射声穿透等物理效应，并构建高效直角波导和分束、声隐身、平面放大声学超透镜等一系列原型功能器件。本项目的研究成果发展了利用声学超构介质实现对声波传输、散射及折射等方面进行超常规人工调控的方法，在多种声学超构介质的设计、制备与相关新原理声学功能器件集成等方向取得了多项具有原创性的成果，不但丰富了声学学科的基础理论，还推动了声学功能器件技术的发展。