Tunable acoustic double negativity metamaterial

5 pags, 3 figsMan-made composite materials called metamaterials allow for the creation of unusual wave propagation behavior. Acoustic and elastic metamaterials in particular, can pave the way for the full control of sound in realizing cloaks of invisibility, perfect lenses and much more. In this work we design acousto-elastic surface modes that are similar to surface plasmons in metals and on highly conducting surfaces perforated by holes. We combine a structure hosting these modes together with a gap material supporting negative modulus and collectively producing negative dispersion. By analytical techniques and full-wave simulations we attribute the observed behavior to the mass density and bulk modulus being simultaneously negative. © 2012 Macmillan Publishers Limited. All rights reserved.J. C. gratefully acknowledges financial support from the Carlsberg Foundation under Contract No. MetaSound 2011-01-0099. J. L. thanks for the support from City University of Hong Kong SRG grant number 7002598 and the GRO program of Samsung Advanced Institute of Technology. J. C. would like to thank Luis Martin-Moreno for stimulating discussions