Confined acoustic line modes within a glide-symmetric waveguide

Abstract

Confined coupled acoustic line-modes supported by two parallel lines of periodic holes on opposite surfaces of a glide-symmetric waveguide have a hybrid character combining symmetric and anti-symmetric properties. These hybrid coupled acoustic line-modes have a near constant group velocity over a broad frequency range as no band gap is formed at the first Brillouin zone boundary. We show that the hybrid character of these confined modes is tuneable as a function of the spacing between the two surfaces. Further we explore how the band-gap reappears as the glide symmetry is broken.

Acoustic metasurfaces with Frieze symmetries

“…3,4 The effects of symmetry, and its strategic breaking, have been utilized across wave physics, from the passive beam-steering applications to topological surfaces and insulators. [5][6][7][8][9][10] There has been a recent interest in the design of reconfigurable one-dimensional (1D) waveguiding structures, [11][12][13][14] whereby the symmetries of the unit cell are used, or broken, to tailor the dispersion of supported modes. Glide-symmetry has been extensively investigated in the electromagnetic regime, [15][16][17][18] with notable studies done by Hessel et al in 1973 19 with periodically loaded waveguides.…”