Glide-Reflection Symmetric Topological Phononic Crystal Waveguide

Abstract

International audienceThe topological backscattering immunity of waves guided along a domain wall is associated with symmetry protection in valley-Hall and quantum-Hall phononic crystal waveguides. This desirable property results from a topological transition at a Dirac point of the 2D crystal, leading to the opening of an initially closed band gap but to a limited available bandwidth compared to wide band gap topological trivial crystals. Introducing a glide-symmetric dislocation of a square lattice crystal of circular inclusions, we show that a pair of wide-bandwidth, single-mode, and symmetryprotected guided waves are created, without resorting to bulk boundary correspondence. A demonstration experiment is performed with acoustic waves in water, at ultrasonic frequencies. The concept further applies to different types of waves, including elastic waves in solids, but also optical and electromagnetic waves