Issue 17, 2019

Three-dimensional acoustic sub-diffraction focusing by coiled metamaterials with strong absorption

Abstract

The diffraction limit restricts the smallest diameter of a wave's focal spot in a homogeneous medium to no less than half of the operating wavelength. The diffraction limit originates from the interference between converging and diverging waves, however, in this paper, a focus spot beyond the diffraction limit is realized by employing a point-like sink at the focus point to change this interference, thereby eliminating or reducing the diverging waves, using subwavelength coiled acoustic metamaterial absorbers. This sub-diffraction focusing effect is intuitively demonstrated in a number of three-dimensional time-reversal acoustic experiments, for which a planar coiled structure and two types of hemispherical coiled structures were respectively designed. Here, these linear, planar and spherical sub-diffraction focusing results are detailed and the corresponding physical mechanisms are discussed.

Graphical abstract: Three-dimensional acoustic sub-diffraction focusing by coiled metamaterials with strong absorption

Supplementary files

Article information

Article type
Paper
Submitted
05 Marts 2019
Accepted
04 Apr. 2019
First published
04 Apr. 2019

J. Mater. Chem. C, 2019,7, 5131-5138

Three-dimensional acoustic sub-diffraction focusing by coiled metamaterials with strong absorption

F. Ma, J. Chen and J. H. Wu, J. Mater. Chem. C, 2019, 7, 5131 DOI: 10.1039/C9TC01243E

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