Underwater Acoustic Bottle Beam Generated by Latticed Pentamode Metasurface

In this paper, we design an underwater acoustic metasurface using a 2-dimensional version of the pentamode lattice to convert a plane wave into a circular bottle beam. The energy of the plane wave transmitted through the designed metasurface mainly focuses on the bottle edge and forms a dark zone. The simulated results demonstrate that a rigid obstacle in the dark zone has hardly any damage on the bottle beam, which means that the bottle beam is robust against the scattering from the obstacle. Moreover, the influence of incident angle on the bottle beam is also analyzed. It is shown that the change of the incident angles can changes the shape of the bottle beam. However, the dark zone still exists and is robust against the obstacle. The underwater acoustic bottle beam may have interesting potential applications in biomedical imaging and in vivo cell manipulation.