Phonon diode and waveguide using topological Kagome lattice

Recent progress in topological mechanics revealed a series of lattice structures that exhibit topologically protected edge floppy modes. These edge modes, while being zero frequency and not propagating in the ideal-lattice limit, can gain finite frequency and propagate with positive velocity when additional interactions such as next-nearest-neighbor bonds are added. In this talk, we present our recent designs of phonon diode and waveguide based on the topological kagome lattice. It is well known that systems with time-reversal symmetry in the linear regime exhibit “reciprocity”, namely equal wave transmission rate from point A to B and B to A in space, making phonon diode challenging to realize. Our design takes advantage of topological edge modes and geometric nonlinearity in topological kagome lattices, and demonstrate non-reciprocal transport of sound waves in these lattices. We also show results on phonon waveguiding via these topological modes at interfaces between different types of topological kagome lattice. Our results open the door to realizing novel acoustic metamaterials that exhibit topologically protected nonreciprocal wave transport.