报告人：杨海教授，昆明学院
邀请人：龚云贵教授
报告时间：2025年4月28日（周一） 9：30
报告地点：龙赛理科南楼414会议室

报告人简介：
杨海，昆明学院二级教授，云南省中青年学术与技术带头人，省委联系专家，享受云南省特殊津贴。1993年在华中科技大学获得硕士学位，2002年破格晋升为教授。主持完成项目11项，其中国家基金项目3项。获得过云南省自然科学二等奖及三等奖各1项。发表高水平学术论文四十余篇。

报告摘要：
Valley interface states, resulting in acoustic valley Hall topological insulators, have recently become a hot topic in the study of acoustic systems. On the basis of structural diversity and potential applications, we construct a two-dimensional triangular-lattice phononic crystal with C3v-symmetric scatterers, and obtain two distinct valley Hall phases with nonvanishing valley Chern indices by rotating the scatter ers. We numerically calculate the dispersion relations of these valley Hall phases including two kinds of interfaces, and find that valley interface states exist at not only the zigzag interface but also the armchair interface. We demonstrate the acoustic splitting and merging of valley interface states in the cross-waveguides, and numerically achieve the XOR and OR logic functions. We also design three com plicated waveguides by assembling phononic crystals with distinct valley Hall phases. By experimental measurements in these waveguides, we successfully implement one-, two-, and three-channel topological transport, which provide an equal splitting ratio at two ports. Furthermore, we achieve asymmetric transport in a sonic valley Hall insulator, by introducing asymmetric edge states, thus we carry out waveguide with an arbitrary splitting ratio at the two ports in the other work. As an example, the sonic topological splitter with a splitting ratio of 1/2 at the ports is demonstrated in the simulation and experiment, and the robust transmission properties of this sonic splitter with defects are verified. Those results have great potential for manipulating the distribution of sonic energy, and possibly provide a design route exploiting valley interface states to fabricate multichannel acoustic communication devices.

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