基于声学超构表面的聚焦型声二极管设计、制备与应用

High intensity focused ultrasound has attracted wide attention as a novel noninvasive therapeutic technique of tumors. But in clinical treatments, there exists a problem that high intensity reflection acoustic waves can easily damage focus transducers and harm human tissues. It is of great academic significance and application value to develop an acoustic focusing type diode with both unidirectional transmission and focusing performances. In this project, based on the recent researches of acoustic unidirectional transmission and focusing effects, we design ultrathin broadband metasurface units, and analyze coupling mechanisms of the acoustic unidirectional transmission and focusing effects. In addition, we study new mechanisms of an acoustic unidirectional and focusing effect based on acoustic metasurfaces by introducing subwavelength and self-bending focusing effects in detail, and explore accurate control of focus shape and focal length. Moreover, we attach high importance to the experimental studies of the acoustic unidirectional and focusing effect, which is aimed at the design principle, fabrication technique and performance control method of the acoustic unidirectional and focusing device. Furthermore, we discuss the possibility of the application or even enormous change of the acoustic unidirectional and focusing device in the fields of medical ultrasound diagnosis and treatment. The result which is rich in basic academic significance in the field of acoustic metamaterials, is expected to be used in many important fields, such as medical ultrasound, containing potential economic values.

高强度聚焦超声作为一种新型非介入治疗肿瘤技术引起人们广泛的关注。但在临床治疗中，存在着高强度反射声波极易损坏聚焦换能器及其伤害人体健康组织的问题，因此，研制同时具备声单向传输与聚焦性能的聚焦型声二极管，具有重要的学术意义与应用价值。本项目基于申请人近年来在声单向传输与声聚焦方面的研究基础，设计超薄宽带的超构表面单元，分析声单向传输与声聚焦的耦合机理，引入亚波长聚焦与自弯曲聚焦等思路，系统研究基于声学超构表面的宽带聚焦声单向传输的新机制，探索精确控制声焦点形状与焦距的方案，深入开展针对聚焦声单向传输效应的实验研究，旨在提出聚焦声单向器件的设计原理、制备技术及其性能调控方法，并探讨聚焦声单向器件在医学超声诊断与治疗等关键领域中产生应用甚至引起变革的可能性，其成果不仅在声学超构材料领域富含基础性的学术意义，更有望应用于医学超声等重要领域，蕴含着潜在的经济价值。

项目深入探索聚焦声单向传输器件的设计原理、制备技术及其性能调控方法，分析声单向传输与声聚焦的耦合机理，研究宽带聚焦声单向传输的新机制，设计制备多种聚焦声单向传输器件。主要创新点包括：(1) 提出了基于双层声超表面、双层热声相控阵列、模式转换单元及近零折射蜷曲空间单元等结构的聚焦声单向传输透镜，基于相控阵列的聚焦声单向传输三棱镜，基于合成规范场的声单向反射镜。实现了多种类型高性能聚焦声单向传输器件。(2) 提出了基于不同个数的腔结构与V结构相控单元、热声相控单元、近零折射蜷曲空间单元等结构的声聚焦透镜、两元相控声聚焦透镜、对称声艾里束声聚焦透镜，可弯折声聚焦透镜及贝塞尔束超长聚焦透镜，基于准三维超表面的声聚焦透镜及贝塞尔束声涡旋聚焦透镜，基于复合Mie共振的声聚能器，设计制备了多种宽频带声聚焦器件。(3)首次提出基于三维声子晶体的三重拓扑简并点、双重简并拓扑节面、拓扑八极子，基于三维拓扑绝缘体的缺陷诱导声涡旋态，基于扭曲拓扑缠绕的非厄米声趋肤效应，非配对光狄拉克点及基于无序光子晶体的拓扑安德森绝缘体等多种新型拓扑绝缘体及其相关的功能器件。除此之外，项目提出了多种基于声超材料、超表面、超声栅的反射镜、声逻辑运算、隔声吸声及定向声传输方案，发展了多种声波操控新机制及其相关声学器件的设计原理与制备技术。项目共发表学术论文44篇，其中SCI检索论文42篇 (含一区Top期刊Nat. Phys., Sci. Adv., Adv. Mater., Adv. Sci.各1篇，Nat. Commun. 5篇及PRL2篇，高被引论文1篇)，EI检索论文2篇；授权发明专利3项，申请发明专利3项; 培养博士后2名，博士生2名，硕士生8名。项目成果不仅在声超材料、超表面及拓扑绝缘体等领域富含基础性的学术意义，更有望应用于国防安全及经济建设等重要领域，蕴含着潜在的经济价值。