Acoustic field enhancement and subwavelength imaging by coupling to slab waveguide modes

Johan Christensen, F. J. García de Abajo

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We present a theoretical study on the amplification of evanescent sound waves produced by coupling to trapped modes hosted by a fluidic planar waveguide. Total internal reflection at interfaces of different refractive indexes can be frustrated by the introduction of a slow slab waveguide which is leading to a gigantic field enhancement, useful for sensitive transducers and acoustic shock lithotripsy. The mechanism behind the evanescent field coupling that is also known as tunnelling barrier penetration in quantum mechanics is here adopted for its use in an acoustic superlens. The higher spatial harmonics produced by a subwavelength object can couple to trapped modes of the slow waveguide and be reproduced as an image at a distant plane. We suggest a practical implementation of these ideas by means of a silicone rubber slab containing positive acoustic wave propagation parameters.
Original languageEnglish
Article number164103
JournalApplied Physics Letters
Volume97
Issue number16
Number of pages3
ISSN0003-6951
DOIs
Publication statusPublished - 2010
Externally publishedYes

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