Journal Article Time-domain imaging of gigahertz surface waves on an acoustic metamaterial

Otsuka, Paul H.  ,  Mezil, Sylvain  ,  Matsuda, Osamu  ,  Tomoda, Motonobu  ,  Maznev, Alexei A.  ,  Gan, Tian  ,  Fang, Nicholas  ,  Boechler, Nicholas  ,  Gusev, Vitalyi E.  ,  Wright, Oliver B.

20p.13026 , 2018-01-22 , IOP Publishing
We extend time-domain imaging in acoustic metamaterials to gigahertz frequencies. Using a sample consisting of a regular array of similar to 1 mu mdiameter silica microspheres forming a two-dimensional triangular lattice on a substrate, we implement an ultrafast technique to probe surface acoustic wave propagation inside the metamaterial area and incident on the metamaterial from a region containing no microspheres, which reveals the acoustic metamaterial dispersion, the presence of band gaps and the acoustic transmission properties of the interface. A theoretical model of this locally resonant metamaterial based on normal and shear-rotational resonances of the spheres fits the data well. Using this model, we show analytically how the sphere elastic coupling parameters influence the gap widths.

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