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

Waveguiding in general and acoustic waveguiding in particular are possible under the condition of a transverse “discontinuity” or modulation in the refractive index. We propose a radically different approach that relies on imposing spinning on a column of air, leading to highly modified acoustic refractive indices for specific azimuthal modes. This result may be leveraged to realize not only the airborne acoustic counterpart of an optical fiber, i.e., an acoustic spinning fiber, but also a nonreciprocal unidirectional waveguiding mechanism, reminiscent of an “acoustic Zeeman effect.” The concept is demonstrated in the realm of acoustics, but may be applicable to other wave systems, e.g., in elastodynamics.