META Conference, META'12

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Acoustic Resonators for Far Field Control of Sound on a Subwavelength Scale
Geoffroy Lerosey, Fabrice Lemoult, Mathias Fink

Last modified: 2011-12-30

Abstract


In this talk we will prove experimentally that broadband sounds can be controlled and focused at will on a subwavelength scale using acoustic resonators. We demonstrate our approach in the audible range with soda cans, that is, Helmholtz resonators, and commercial computer speakers. We show that diffraction limited sound fields convert efficiently into sub-diffraction modes in the collection of cans that can be controlled coherently in order to obtain focal spots as thin as 1/25th of a wavelength in air. We establish that subwavelength acoustic pressure spots are responsible of a strong enhancement of the acoustic displacement at focus. Finally we will present initial results of collective modes in arrays of elastic resonators which promise to be interesting candidates for a transposition of the concept to elastic waves.

Keywords


metamaterials, subwavelength focusing, hybridization band gaps