Sound Waveguiding by Spinning: An Avenue towards Unidirectional Acoustic Spinning Fibers

TL;DR

This paper introduces a novel method for acoustic waveguiding using spinning air columns, enabling unidirectional and nonreciprocal wave propagation, potentially inspiring new fiber-like acoustic devices and applications across wave systems.

Contribution

It proposes a new approach to acoustic waveguiding based on spinning air columns, leading to high refractive indices and unidirectional waveguiding, a significant departure from traditional methods.

Findings

Demonstrates high modified acoustic refractive indices for azimuthal modes

Shows potential for unidirectional, nonreciprocal waveguiding

Applicable to other wave systems like photonics and elastodynamics

Abstract

Waveguiding in general and acoustic waveguiding in particular are possible at the condition of having a transverse "discontinuity" or modulation of the refractive index. We propose here a radically different approach that relies on imposing spinning on a column of air, leading to high modified acoustic refractive indices for specific azimuthal modes. Such discovery may be leveraged to realize not only the airborne acoustic counterpart of the optical fiber, i.e., the acoustic spinning fiber (ASF), but also nonreciprocal unidirectional waveguiding mechanism, reminiscent of the ''acoustic Zeeman effect''. The concept is demonstrated in the realm of acoustics, yet it can be applicable to other wave systems, e.g., photonics or elastodynamics.