Negative refraction of phonons and acoustic lensing effect of a crystalline slab
Negative refraction of phonons and acoustic lensing effect of a crystalline slab
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DOI：
10.1103/physrevb.70.174308
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发表时间：
2004-11-01
影响因子：
3.7
通讯作者：
Tamura, S
中科院分区：
文献类型：
--
作者：
Imamura, K;Tamura, S
我们研究如何良好的一个大的弹性各向异性的大块晶体固体平板表现出声子或声波的透镜作用。在几何声学近似下，分析了理想弹性固体平板声子透镜的慢度面和群速度面。这些表面与现有的块状晶体（锌晶体）与六方对称的相应表面进行比较。为了证明透镜效应，我们计算了从各向同性介质（在透镜的一侧）中的点源发射的声子的强度分布，通过平板透镜传播，然后传输到另一侧的各向同性介质中。用时域有限差分法对声波进行了类似的计算，以观察几何声学近似中忽略的影响，即有限波长、模式转换和界面处有限透射的影响。
We study how good a flat slab of a bulk crystalline solid with a large elastic anisotropy exhibits a lensing action for phonons or sound waves. The slowness and group-velocity surfaces of an ideal elastic solid for a flat phonon lens are analyzed in the geometrical acoustic approximation. These surfaces are compared with the corresponding surfaces of an existing bulk crystal (a zinc crystal) with hexagonal symmetry. To demonstrate the lensing effect we calculate the intensity distribution of phonons emitted from a point source in an isotropic medium (on one side of the lens), propagating through the slab lens and then transmitted into the isotropic medium in the other side. A similar calculation for sound waves with a finite-difference-time-domain method is performed to see the effects neglected in the geometrical acoustic approximation, that is, the effects of finite wavelength, mode conversion, and finite transmission at the interfaces.