Experimental Evidence of Robust Acoustic Valley Hall Edge States in a Nonresonant Topological Elastic Waveguide

Inspired by recent discoveries of topological phases of matter in quantum physics, there has been a rapidly growing research effort to create their analogues in classical wave systems, especially to realize nonscattering waveguides in the presence of disorder. This study presents a robust elastic waveguide based on the acoustic analogue of the quantum valley Hall effect in a nonresonant phononic elastic structure. Elastic waves travel around sharp corners in the waveguide without reflection, and can also be unidirectionally excited. These features break the limits of conventional waveguides and have great potential in acoustic signal processing and vibration control.