固体中弹性波零折射率超常材料的特性研究

Metamaterials have recently attracted wide concern because of their unique property that traditional materials don't have. Among metamaterials, zero index metamaterials have been used to realize many interesting phenomena for the phase of wave throughout the whole zero index metamaterials is essentially constant. But most of the current zero index metamaterials researches are confined to electromagnetic / acoustic waves system. However, the coexistence of longitudinal wave and transverse wave in solid makes the propagation of elastic waves more complicated than that of electromagnetic / acoustic waves, hence the research of elastic waves zero index metamaterials in solid is insufficient. In view of this, this project focuses on elastic waves zero index metamaterials in solid and explores its physical properties systematically: Study the propagation characteristics of longitudinal / transverse waves in different zero index metamaterials in which one or more effective elastic parameters are zero; introduce anisotropy scatters to realize the separate and independent control of longitudinal / transverse waves; explore how to realize zero refractive index of flexural wave / Lamb wave in solid plate so as to provide a feasible system for further research and realize many solid state devices such as controllable elastic waves waveguide and elastic waves cloaking, etc. This project will help people learn more about the propagation characteristics of elastic waves in metamaterials from the perspective of physical concepts, which is scientifically meaningful and potentially valuable.

超常材料因为具有传统材料所不具备的超常性质近年来引起了广泛的关注。这其中，零折射率超常材料因为具有波在其中传播时不存在相位变化的特性而被用来实现许多有趣的现象。但是目前大部分零折射率超常材料研究局限于电磁波/声波体系。而在固体中因为纵/横波的同时存在，使得弹性波的传播问题要比电磁波/声波复杂，从而使得弹性波零折射率超常材料的研究工作仍然非常欠缺。有鉴于此，本项目将固体中弹性波零折射率超常材料作为研究对象，系统地研究其物理性质：研究一个或多个等效参数为零的各种弹性零折射率超常材料中纵/横波的传播特性，通过引入各向异性散射体实现纵/横波的分离独立操控，探索在固体平板中实现弯曲波/Lamb波的零折射率，为实验研究提供切实可行的体系，并利用其实现可控弹性波波导，弹性波隐身等多种固体器件。本研究项目的开展将有助于从物理概念上拓展人们对弹性波在超常材料中传播特性的认识，具有科学意义和潜在的应用价值。

本项目主要对声波在声学各向异性超常材料中的传播性质进行了系统深入的研究，主要包括：利用各向异性零密度超常材料实现多声源的鲁棒交叠效果；得到利用声学超常材料实现多极辐射增强的严格解析模型；实现利用轨道角动量的声波分路器；深亚波长实心迷宫状棒对声音的超散射；超越体模量的超常流体。本项目的研究取得了一系列有意义的研究成果。到目前为止，在该基金支持下，已发表第一或通讯作者SCI论文5篇，包含Phys.Rev. Lett. 1篇，Phys. Rev. Applied 2篇，Phys. Rev. B 1篇, Appl. Phys. Lett. 1篇，另外在Appl. Phys. Lett.上发表合作论文3篇