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

• Main Authors: Otsuka, Paul H (Author), Mezil, Sylvain (Author), Matsuda, Osamu (Author), Tomoda, Motonobu (Author), Boechler, Nicholas (Author), Gusev, Vitalyi E (Author), Wright, Oliver B (Author), Maznev, Alexei (Contributor), Gan, Tian (Contributor), Fang, Xuanlai (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Chemistry (Contributor), Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science (Contributor), Massachusetts Institute of Technology. Department of Mechanical Engineering (Contributor)
• Format: Article
• Language: English
• Published: IOP Publishing, 2018-11-19T22:38:33Z.
• Subjects: Article
• Online Access: Get fulltext

 We extend time-domain imaging in acoustic metamaterials to gigahertz frequencies. Using a sample consisting of a regular array of ~1 μm diameter 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.