Experimental Demonstration of Acoustic Valley Hall Topological Insulators with the Robust Selection of C3v-Symmetric Scatterers

Topological insulators continue to be a hot topic in research, particularly for their backscattering immunity. While previous works have restricted consideration to identical primitive unit cells, this work demonstrates an $a\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}c$ valley topological insulator, with robust selection of ${C}_{3v}$ symmetric scatterers in adjacent sonic crystals. This study also presented a functional device, the valley-selective cross-waveguide beam splitter, in the proposed acoustic system. The ability to select scatterers found in this work may illuminate further possibilities for designing acoustic topological-insulator-based devices with flexible structures.