Extraordinary focusing of sound above a soda can array without time reversal
Recently, Lemoult et al (2011 Phys. Rev. Lett. 107 064301) used time reversal to focus sound above an array of soda cans into a spot much smaller than the acoustic wavelength in air. In this study, we show that equally sharp focusing can be achieved without time reversal, by arranging transducers ar...
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/98377 https://orcid.org/0000-0001-5713-629X |
| _version_ | 1826199626157391872 |
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| author | Gu, Gen Sun, Shu-yuan Xu, Jun Shen, Yong Zhang, Shu-yi Maznev, Alexei Fang, Nicholas Xuanlai |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Gu, Gen Sun, Shu-yuan Xu, Jun Shen, Yong Zhang, Shu-yi Maznev, Alexei Fang, Nicholas Xuanlai |
| author_sort | Gu, Gen |
| collection | MIT |
| description | Recently, Lemoult et al (2011 Phys. Rev. Lett. 107 064301) used time reversal to focus sound above an array of soda cans into a spot much smaller than the acoustic wavelength in air. In this study, we show that equally sharp focusing can be achieved without time reversal, by arranging transducers around a nearly circular array of soda cans. The size of the focal spot at the center of the array is made progressively smaller as the frequency approaches the Helmholtz resonance frequency of a can from below, and, near the resonance, becomes smaller than the size of a single can. We show that the locally resonant metamaterial formed by soda cans supports a guided wave at frequencies below the Helmholtz resonance frequency. The small focal spot results from a small wavelength of this guided wave near the resonance in combination with a near field effect making the acoustic field concentrate at the opening of a can. The focusing is achieved with propagating rather than evanescent waves. No sub-diffraction-limited focusing is observed if the diffraction limit is defined with respect to the wavelength of the guided mode in the metamaterial medium rather than the wavelength of the bulk wave in air. |
| first_indexed | 2024-09-23T11:22:54Z |
| format | Article |
| id | mit-1721.1/98377 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:22:54Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/983772022-09-27T19:09:47Z Extraordinary focusing of sound above a soda can array without time reversal Gu, Gen Sun, Shu-yuan Xu, Jun Shen, Yong Zhang, Shu-yi Maznev, Alexei Fang, Nicholas Xuanlai Massachusetts Institute of Technology. Department of Chemistry Massachusetts Institute of Technology. Department of Mechanical Engineering Maznev, Alexei Xu, Jun Fang, Nicholas Xuanlai Recently, Lemoult et al (2011 Phys. Rev. Lett. 107 064301) used time reversal to focus sound above an array of soda cans into a spot much smaller than the acoustic wavelength in air. In this study, we show that equally sharp focusing can be achieved without time reversal, by arranging transducers around a nearly circular array of soda cans. The size of the focal spot at the center of the array is made progressively smaller as the frequency approaches the Helmholtz resonance frequency of a can from below, and, near the resonance, becomes smaller than the size of a single can. We show that the locally resonant metamaterial formed by soda cans supports a guided wave at frequencies below the Helmholtz resonance frequency. The small focal spot results from a small wavelength of this guided wave near the resonance in combination with a near field effect making the acoustic field concentrate at the opening of a can. The focusing is achieved with propagating rather than evanescent waves. No sub-diffraction-limited focusing is observed if the diffraction limit is defined with respect to the wavelength of the guided mode in the metamaterial medium rather than the wavelength of the bulk wave in air. United States. Office of Naval Research. Multidisciplinary University Research Initiative (Grant N00014-13-1-0631) 2015-09-08T12:21:36Z 2015-09-08T12:21:36Z 2015-04 2015-01 Article http://purl.org/eprint/type/JournalArticle 1367-2630 http://hdl.handle.net/1721.1/98377 Maznev, A A, Gen Gu, Shu-yuan Sun, Jun Xu, Yong Shen, Nicholas Fang, and Shu-yi Zhang. “Extraordinary Focusing of Sound Above a Soda Can Array Without Time Reversal.” New J. Phys. 17, no. 4 (April 1, 2015): 042001. © 2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft https://orcid.org/0000-0001-5713-629X en_US http://dx.doi.org/10.1088/1367-2630/17/4/042001 New Journal of Physics Creative Commons Attribution http://creativecommons.org/licenses/by/3.0/ application/pdf IOP Publishing IOP Publishing |
| spellingShingle | Gu, Gen Sun, Shu-yuan Xu, Jun Shen, Yong Zhang, Shu-yi Maznev, Alexei Fang, Nicholas Xuanlai Extraordinary focusing of sound above a soda can array without time reversal |
| title | Extraordinary focusing of sound above a soda can array without time reversal |
| title_full | Extraordinary focusing of sound above a soda can array without time reversal |
| title_fullStr | Extraordinary focusing of sound above a soda can array without time reversal |
| title_full_unstemmed | Extraordinary focusing of sound above a soda can array without time reversal |
| title_short | Extraordinary focusing of sound above a soda can array without time reversal |
| title_sort | extraordinary focusing of sound above a soda can array without time reversal |
| url | http://hdl.handle.net/1721.1/98377 https://orcid.org/0000-0001-5713-629X |
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