Experimental validation of acoustic valley Hall edge states in a nonresonant topological elastic waveguide (Conference Presentation)

Abstract

We experimentally demonstrate the existence and the characteristics of acoustic quantum valley Hall edge states in a continuous topological elastic waveguide. The waveguide is obtained by subtractive manufacturing, hence cutting a non-resonant truss-like lattice from an initially uniform aluminum thin plate. The fabricated lattice includes two different domains characterized by broken space inversion symmetry and contrasted with each other in order to create a physical interface (i.e. a domain wall) capable of inducing a topological transition. Guided modes in the waveguide are generated using piezoelectric actuators and are measured using laser vibrometry. Data show the existence of well-confined edge states with negligible backscattering at the sharp corners along the domain wall. A methodology to precisely excite a uni-directional edge state is also demonstrated. In addition to the experiment results, the coupling between valley modes is also further investigated and linked to a chiral flux of the mechanical energy.