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Acoustic wave focusing by 2.5D graded index lens

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posted on 2023-06-10, 04:53 authored by YUANYAN ZHAOYUANYAN ZHAO, Sriram Subramanian, Gianluca MemoliGianluca Memoli
Three dimensional sound convergence in air underpins applications ranging from localized acoustic experiences to levitation. Most current solutions, however, are challenging to scale-up: they either require complex electronics or intricate geometries. In this paper, we propose a solution based on sonic crystals: an extruded 2D hexagonal lattice array of rigid cylinders with gradient diameters, capable of focusing in 3D emission of a standard loudspeaker at audio frequencies, which we call a 2.5D lens. First, we use finite-element simulations to describe the underpinning theory in terms of the band structure and equifrequency contours. We then describe how we manufactured two lenses, one of which has a focal length smaller than the wavelength, and compare pressure with simulations. Our measurements not only show good agreement with simulations but also highlight how the efficiency of such lenses strongly depends on how the sound is delivered to them.

History

Publication status

  • Published

File Version

  • Published version

Journal

Applied Physics Letters

ISSN

0003-6951

Publisher

AIP Publishing

Volume

119

Page range

a141907 1-8

Department affiliated with

  • Informatics Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2022-09-27

First Open Access (FOA) Date

2022-09-27

First Compliant Deposit (FCD) Date

2022-09-27

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