Topological acoustic sensing using the geometric phase
Keith Runge, Pierre Alix Deymier · The Journal of the Acoustical Society of America · 2024
We introduce a method, topological acoustic sensing, which exploits changes in the geometric phase of acoustic waves to sense defects in some structure or environment. This method is illustrated in two cases of perturbations taking the form of (1) a mass defect located on an array of coupled acoustic waveguides, and (2) a small subwavelength object on a flat surface submerged under water. We represent the state of the acoustic field in the unperturbed and perturbed cases as multidimensional vectors. The change in geometric phase is obtained by calculating the angle between those vectors. This angle represents a rotation of the state vector of the wave due to scattering by the perturbation. By exploiting sharp topological features spanned by the acoustic field multidimensional state vector, we show that this geometric phase sensing modality can have higher sensitivity than magnitude-based sensing approaches.