Subwavelength Sound Focusing and Imaging Via Gradient Metasurface-Enabled Spoof Surface Acoustic Wave Modulation

Tuo Liu, Fei Chen, Shanjun Liang, He Gao, Jie Zhu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

49 Citations (Scopus)


Manipulating acoustic waves beyond the diffraction limit offers alternative possibilities to many applications in wave physics. Here, we show that a gradient-index acoustic metasurface is able to achieve this purpose by modulating airborne sound at subwavelength scales via the local-resonance-controlled spoof surface acoustic waves. From the dispersion relation of such a surface mode, a design approach of explicitly correlating the effective refractive index with the geometrical unit-cell parameters can be obtained. With one carefully designed gradient-index acoustic metasurface constructed using locally resonant elements, we demonstrate the experimental realizations of both subwavelength plane-wave sound focusing and super-resolution acoustic imaging. This work provides a feasible pathway to the subwavelength manipulation of airborne sound. Moreover, it offers an ideal experimental platform to directly observe how acoustic energy flow is governed by refractive-index modulation. The proposed design approach can be easily applied to various spoof surface acoustic wave devices that demand gradient index distribution.

Original languageEnglish
Article number034061
JournalPhysical Review Applied
Issue number3
Publication statusPublished - 26 Mar 2019

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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