Sound Isolation and Giant Linear Nonreciprocity in a Compact Acoustic Circulator

Acoustic isolation and nonreciprocal sound transmission are highly desirable in many practical scenarios. They may be realized with nonlinear or magneto-acoustic effects, but only at the price of high power levels and impractically large volumes. In contrast, nonreciprocal electromagnetic propagatio...

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Bibliographic Details
Published in:	Science (American Association for the Advancement of Science) 2014-01, Vol.343 (6170), p.516-519
Main Authors:	Fleury, Romain, Sounas, Dimitrios L., Sieck, Caleb F., Haberman, Michael R., Alù, Andrea
Format:	Article
Language:	eng
Subjects:	Acoustic modes Acoustic resonance Acoustics Angular momentum Audio frequencies Electromagnetics Propagation Sound Sound propagation Sound transmission Sound waves Wave propagation Zeeman effect
Online Access:	Get full text
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Summary:	Acoustic isolation and nonreciprocal sound transmission are highly desirable in many practical scenarios. They may be realized with nonlinear or magneto-acoustic effects, but only at the price of high power levels and impractically large volumes. In contrast, nonreciprocal electromagnetic propagation is commonly achieved based on the Zeeman effect, or modal splitting in ferromagnetic atoms induced by a magnetic bias. Here, we introduce the acoustic analog of this phenomenon in a subwavelength meta-atom consisting of a resonant ring cavity biased by a circulating fluid. The resulting angular momentum bias splits the ring's azimuthal resonant modes, producing giant acoustic nonreciprocity in a compact device. We applied this concept to build a linear, magnetic-free circulator for airborne sound waves, observing up to 40-decibel nonreciprocal isolation at audible frequencies.
ISSN:	0036-8075 1095-9203