Pseudospin-dependent acoustic topological insulator by airborne sonic crystals with a triangular lattice

Abstract

We report both experimentally and numerically that a pseudospin-dependent acoustic topological insulator is realized based on airborne triangular-lattice sonic crystals with special gear-like rods. By changing structure parameters of the rods in sonic crystals, accidental double Dirac cones and a band inversion phenomenon are obtained successively. In topological waveguides constructed by two sonic crystals with dissimilar topological phases, the topological one-way transports of pseudospin-dependent edge modes are observed. More importantly, the topologically robust sound propagations against two types of defects are also experimentally demonstrated. Our results open a new venue to design pseudospin-dependent topological insulators with versatile applications.