For classical waves such as light or sound, diffraction sets a natural limit on how finely the details of an object can be recorded on its image. Recently, various optical superlenses based on the metamaterials concept have shown the possibility of overcoming the diffraction limit. Similar two-dimensional (2D) acoustic hyperlens designs have also been explored. Here we demonstrate a 3D holey-structured metamaterial that achieves acoustic imaging down to a feature size of λ/50. The evanescent field components of a subwavelength object are efficiently transmitted through the structure as a result of their strong coupling with Fabry-Pérot resonances inside the holey plate. This capability of acoustic imaging at a very deep-subwavelength scale may open the door for a broad range of applications, including medical ultrasonography, underwater sonar and ultrasonic non-destructive evaluation. © 2011 Macmillan Publishers Limited. All rights reserved.

This work has been partially financially supported by the Spanish Ministry of Science under projects MAT2008-06609-C02 and CSD2007-046-Nanolight.es. J.Z. and X.Z. acknowledge support from the US Office of Naval Research (grant number N00014-07-1-0626).

Peer Reviewed