Graded-Index Metamaterial Waveguides: An Innovative Approach to Acoustic Wave Control

声波在许多应用中扮演着重要的角色，例如国土安全(例如声纳系统)、医疗保健(例如超声成像)和工业(例如无损损伤检测)。然而，目前能够有效地控制和操纵声波并用于下一代基于声学的设备的功能声学材料有限。该奖项支持通过新型人造声学材料(即声学超材料)引导、压缩、放大和定位声波的基础研究。这些工程材料具有天然材料无法实现的独特特性。这项工作将为开发新型功能声学装置开辟新的途径，有可能克服传统声学技术中遇到的根本限制。包括物理、材料科学、医学、测量科学和能源科学在内的不同学科将从这项研究的不同方面受益。这一奖项还将帮助代表不足的群体更广泛地参与研究，并通过与研究成果相结合的跨学科课程的创新项目来丰富学生的学习经验。通过结合分析、数值和实验研究，这项工作的目标是实现对声波在各种梯度折射率超材料波导中的传播和引导机制、材料色散和有效折射率的基本了解。这些声学超材料的大部分未被探索的特性，包括显著的波压缩和场放大特性，将被研究。这项研究将丰富各向异性超材料领域的知识，并为利用超材料控制和操纵声场提供新的方法。此外，基于基于石墨烯的光纤探头的光纤声扫描系统，将开发一种新的实验方法，这将为声学超材料中的波传播特性的绘制和可视化提供一种全新的途径。此外，在能量耦合、散射和局部化方面，该奖项还可能导致在渐变折射率超材料波导阵列(大块渐变折射率超材料)中发现全新的物理现象。

Acoustic waves play an important role in many applications, such as homeland security (e.g. sonar systems), healthcare (e.g. ultrasound imaging), and industry (e.g., non-destructive damage detections). However, there are currently limited functional acoustic materials that can effectively control and manipulate acoustic waves and be employed for next-generation acoustic-based devices. This award supports fundamental research on guiding, compression, amplification, and localization of acoustic waves through novel artificial acoustic materials (i.e., acoustic metamaterials). These engineered materials possess unique properties that are unachievable in natural materials. This work will open up new avenues towards the development of novel functional acoustic devices, which can potentially overcome the fundamental limitations encountered in conventional acoustic technologies. Various disciplines including physics, material science, medicine, measurement science, and energy sciences will benefit from different facets of this research. This award will also help broaden the participation of underrepresented groups in research and enrich the learning experience of students with innovative projects in an interdisciplinary curriculum integrated with the research findings.Through combined analytical, numerical, and experimental studies, the goal of this work is to achieve a fundamental understanding of the acoustic wave propagation and guiding mechanisms, material dispersion, effective refractive indices in various graded-index metamaterial waveguides. The largely unexplored properties of these acoustic metamaterials, including the remarkable wave compression and field amplification properties, will be investigated. This research will enrich the knowledge in the growing field of anisotropic metamaterials and lead to new methodologies for control and manipulation of acoustic fields with metamaterials. Furthermore, a novel experimental approach based on a fiber optic acoustic scanning system with graphene based fiber optic probes will be developed, which will offer an entirely new way for mapping and visualization of wave propagation properties in acoustic metamaterials. In addition, this award can also lead to the discovery of fundamentally new physical phenomena in graded-index metamaterial waveguides arrays (bulk graded index metamaterials) in terms of energy coupling, scattering, and localization.