Gapless dispersion of acoustic line modes with glide symmetry

Abstract

The effect of glide symmetry on the dispersion of acoustic surface waves supported by lines of open-ended holes in acrylic plates is investigated. Two samples are experimentally characterized, each formed of a pair of such parallel lines, one having glide-symmetry. This glide symmetry removes the condition necessary for the supported even and odd character acoustic surface waves to form standing waves at the first Brillouin zone boundary; there is instead one mixed even-odd hybrid mode. This evolves continuously with increasing frequency to a far greater in-plane wave vector than possible without the glide condition. This paper demonstrates that glide symmetry opens a degree of freedom for the design of acoustic metamaterial devices for the control of acoustic energy on a surface.