We report the experimental realization of acoustic bi-anisotropy by asymmetric acoustic metamaterials (AAMs). Asymmetric phases of reflection coefficients are achieved in different-bilayer AAM with different resonant properties on either side, and asymmetric amplitudes of reflection coefficients are achieved by introducing material loss. The existence of acoustic bi-anisotropy means that the effective parameters on either side are asymmetric. A modified direct method is presented to obtain unified effective parameters, and the calculated unified effective parameters meet the requirements of passive metamaterials. This work explores acoustic bi-anisotropy in asymmetric structures, and provides new avenues to tailor reflection waves.

中文翻译：

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非对称声学超材料中的声学双各向异性

我们报告了通过非对称声学超材料（AAM）的声学双各向异性的实验实现。在两侧具有不同谐振特性的不同双层AAM中，实现反射系数的不对称相位，并且通过引入材料损耗来实现反射系数的不对称幅度。声学双各向异性的存在意味着两侧的有效参数都是不对称的。提出了一种改进的直接方法来获得统一的有效参数，计算出的统一有效参数满足了被动超材料的要求。这项工作探索了非对称结构中的声学双各向异性，并为定制反射波提供了新途径。