Valley-projected edge modes observed in underwater sonic crystals

TL;DR

This paper demonstrates the experimental observation of valley-projected topological edge modes in underwater sonic crystals, opening new avenues for underwater sound manipulation and noise control.

Contribution

It is the first to experimentally realize and observe valley-projected topological edge states in underwater sound systems, expanding topological physics into aquatic environments.

Findings

Direct observation of valley-projected edge modes in underwater sound

Evidence of valley-selective excitation in experiments

Good agreement between experimental data and numerical simulations

Abstract

Recently, the topological physics in acoustics has been attracting much attention. However, all the studies are aimed to elastic or airborne sound systems. Realizing topological insulators for underwater sound is of great importance, since water is another crucial sound medium in addition to solid and air. Here we report an experimental study on the valley-projected edge states for underwater sound. The edge states are directly observed in our ultrasound scanning experiments, together with a solid evidence for the valley-selective excitation. The experimental data agree well with our numerical results. Prospective applications can be anticipated, such as for underwater sound signal processing and ocean noise control.