Manipulation and Experimental Characterization of Higher-Order Topological Corner States in Two-Dimensional Anisotropic SSH Acoustic Lattices

近年来，声子晶体、超表面及超材料等人工微结构的研究取得显著进展，揭示了一系列新颖的物理现象。其中，支持拓扑边界态的人工声学系统的出现，标志着声学人工结构研究迈入新阶段。受凝聚态物理中拓扑序研究的启发，光子晶体、力学系统及准周期结构的拓扑特性被广泛探索。作为一类超越传统金属/绝缘体分类的新物态，声学拓扑绝缘体因其非平庸边界模式展现出无后向散射与缺陷免疫的独特声波传输特性，为声学功能器件的创新设计提供了新范式。文章聚焦于高阶拓扑绝缘体的典型代表——二维Su-Schrieffer-Heeger (SSH)模型，系统阐释其拓扑能带特性，提出一种新型二维SSH声学晶格结构。通过数值仿真成功观测到角态局域化现象，并在实验上首次实现角态声压分布的可控激发与表征。该研究为拓扑声学器件的实际应用奠定了理论与实验基础。In recent decades, the study of artificial microstructures such as phononic crystals, metasurfaces, and metamaterials has achieved remarkable progress, unveiling a series of novel physical phenomena. The emergence of artificial acoustic systems supporting topological boundary states has propelled the research on acoustic structures to new heights. Inspired by developments in condensed matter physics, extensive investigations have been conducted on the topological properties of photonic crystals, mechanical systems, and quasiperiodic structures. As a novel phase of matter transcending conventional metal/insulator classifications, acoustic topological insulators exhibit unique sound wave transport characteristics with nontrivial boundary modes, including backscattering suppression and defect immunity, offering innovative paradigms for designing advanced acoustic devices. This work focuses on the two-dimensional Su-Schrieffer-Heeger (SSH) model—a prototypical higher-order topological insulator. We systematically elucidate its topological band properties and propose a novel 2D SSH-inspired acoustic lattice configuration. Numerical simulations successfully demonstrate corner-state localization, while subsequent acoustic experiments achieve the first controlled excitation and characterization of corner-mode pressure distributions. This study establishes both theoretical and experimental foundations for practical applications of topological acoustic devices.