Topologically robust sound wave transport in two-dimensional phononic crystal with a circular rod arrangement in water

The topologically protected wave propagation offers a novel class of energy and/or information transport via various types of wave carriers. We design an acoustic waveguide with chiral edge states appeared in interfaces of two differently oriented phononic crystals. The structural design of waveguides with spin-type and valley-type topological acoustics and the robustness comparison of acoustic wave propagation in the waveguides are performed using finite element method. Based on these analyses, we propose a valley topological phononic waveguide composed of three circular rods that can be easily fabricated. The waveguide is made with a 3D printed mold and stainless rods. We show that the fabricated waveguide has high robustness for acoustic wave propagation around 400 kHz in water.