Boundary-Induced Helical Bulk Acoustic Transport in LiNbO 3 Thin Films

作者：Zhe Li, Zhen-Hui Qin, Shu-Mao Wu, Chen-Bei Hao, F. M. Pan, Hao Yan, Yi‐Han He, Yan-Chen Zhou, Xuejun Yan, Si‐Yuan Yu, Chunying He, Ming-Hui Lu, Yan-Feng Chen · 发表于：Physical Review Letters · 年份：2026 · DOI：10.1103/x6mm-jgzx · 被引用次数：1 · 研究领域：Acoustic Wave Phenomena Research、Geophysical Methods and Applications、Speech and Audio Processing

We experimentally demonstrate boundary-induced helical bulk states (BI-HBSs) for rf acoustic transport in LiNbO3 thin-film phononic crystals (∼175-200 MHz). A boundary-symmetry selection rule at an accidental Γ-point fourfold degeneracy creates interior bulk channels that couple to wide-aperture interdigital transducers without edge-aperture mismatch. Near-field vibrometry and two-port rf S parameters confirm low-loss propagation with strongly suppressed backscattering through wavelength-scale defects. The helical band also provides slow-wave, low-dispersion delay and phase control on chip.