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arXiv · 2502.18385

Boundary-induced helical bulk acoustic transport in LiNbO3 thin films

Zhe Li·Zhen-Hui Qin·Shu-Mao Wu·Chen-Bei Hao·Fan-Yun Pan·Hao Yan·Yi-Han He·Yan-Shen Zhou·Xue-Jun Yan·Si-Yuan Yu·Cheng He·Ming-Hui Lu·Yan-Feng Chen
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Abstract

We experimentally demonstrate boundary-induced helical bulk states (BI-HBSs) for RF acoustic transport in LiNbO3 thin-film phononic crystals (approximately 175-200 MHz). A boundary-symmetry selection rule at an accidental {\Gamma}-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.

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Zhe Li, Zhen-Hui Qin, Shu-Mao Wu, Chen-Bei Hao, Fan-Yun Pan, Hao Yan, Yi-Han He, Yan-Shen Zhou, Xue-Jun Yan, Si-Yuan Yu, Cheng He, Ming-Hui Lu, Yan-Feng Chen. 2025-02-25. Boundary-induced helical bulk acoustic transport in LiNbO3 thin films. https://doi.org/10.1103/x6mm-jgzx

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