AI 中文总结
本文提出两种基于QVHE和QSHE声学类比的水下SSAW空间-频率解复用机制，经实验验证可稳健实现多频信号分离定位，减少对数字信号处理的依赖，有望应用于水下目标识别与声能采集。
AI 中文摘要
多频声波的高效分离与定位对水下目标识别和声能采集至关重要。由于复杂的流固相互作用，以及在开放系统中实现长距离传输与频率选择定位的结合存在困难，拓扑彩虹捕获的水下应用仍具挑战。本文从理论上开发并实验验证了两种基于量子谷霍尔效应（QVHE）和量子自旋霍尔效应（QSHE）声学类比的水下空间-频率解复用机制。两种机制均采用表面声波（SSAW），其场被限制在结构化表面附近并以倏逝形式衰减到周围水中，无需封闭波导即可开展实验。在QVHE机制中，谷霍尔边缘通道上的空间梯度会改变局域边缘态色散，使不同频率分量定域在不同位置，从而实现频谱与空间解复用；在QSHE机制中，一维拓扑边缘态与频率选择型零维高阶角态耦合，多频信号先沿共同边界稳健传播，再根据频率传输到指定的远端角，形成“传输-后约束”过程，该机制兼具抗缺陷边缘传输、频率选择角定位和远程彩虹捕获的特性。数值模拟与实验验证了频率依赖的定域特性，以及存在结构缺陷时设计的传输路径的稳健性。所提出的开放SSAW平台在物理层实现了稳健的频率解复用，减少了对数字信号处理的依赖，为水下目标识别和频率选择声能采集提供了潜力。
英文摘要
Efficient separation and localization of multifrequency acoustic waves are essential for underwater target recognition and acoustic energy harvesting. The underwater implementation of topological rainbow trapping remains challenging because of complex fluid-solid interactions and the difficulty of integrating long-range transport with frequency-selective localization in an open system. Here, we theoretically develop and experimentally demonstrate two underwater spatial-frequency demultiplexing mechanisms based on the acoustic analogues of the QVHE and QSHE. Both mechanisms employ SSAWs, whose fields are confined near a structured surface and decay evanescently into the surrounding water, enabling experiments without an enclosed waveguide. In the QVHE mechanism, a spatial gradient along a valley-Hall edge channel shifts the local edge-state dispersion, causing different frequency components to become localized at distinct positions and thereby realizing spectral and spatial demultiplexing. In the QSHE mechanism, one-dimensional topological edge states are coupled to frequency-selective zero-dimensional higher-order corner states. Multifrequency signals first propagate robustly along a common boundary and are then transferred to prescribed remote corners according to frequency, producing a transport-then-confinement process. This mechanism combines defect-tolerant edge transport, frequency-selective corner localization, and remote rainbow trapping. Numerical simulations and experiments verify the frequency-dependent localization and the persistence of the designed transport pathways in the presence of structural defects. The proposed open SSAW platform performs robust frequency demultiplexing at the physical layer, reducing reliance on digital signal processing and offering potential for underwater target recognition and frequency-selective acoustic energy harvesting.
