Sound Isolation and Giant Linear Nonreciprocity in a Compact Acoustic Circulator
Sound Isolation and Giant Linear Nonreciprocity in a Compact Acoustic Circulator
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DOI：
10.1126/science.1246957
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发表时间：
2014-01-31
期刊：
影响因子：
56.9
通讯作者：
Alu, Andrea
中科院分区：
文献类型：
--
作者：
Fleury, Romain;Sounas, Dimitrios L.;Alu, Andrea
在许多实际场景中，声学隔离和非互易声传输是非常理想的。它们可以通过非线性或磁声效应来实现，但代价是高功率水平和不切实际的大体积。相比之下，非互易电磁传播通常基于塞曼效应或由磁偏置在铁磁原子中引起的模式分裂来实现。在此，我们在一个由循环流体偏置的共振环形腔构成的亚波长超原子中引入这种现象的声学类似物。由此产生的角动量偏置使环的方位角共振模式分裂，在一个紧凑的装置中产生巨大的声学非互易性。我们应用这一概念构建了一个用于空气声波的线性、无磁环形器，在可听频率下观察到高达40分贝的非互易隔离。
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.