Demultiplexing sound in stacked valley-Hall topological insulators

Abstract

Demulitplexing is used to connect data or signals from one single channel stream to multiple destinations. The streams may be additionally divided through their frequency, polarizations, angular momentum, etc. Here, we show how one is able to demultiplex sound waves at different physical positions and frequency components by employing stacked valley-Hall topological insulators made of merged triangular rigid scatterers. By tuning their two relative angles, we are able to break or restore the underlying lattice symmetry within two topologically independent band gaps. Thus, we experimentally stacked various individually tuned valley-Hall insulators to enable spectrally specific radiated sound to be routed to a particular destination via scattering-immune valley-projected edge states. We foresee that these findings will advance further studies in condensed matter physics, classical wave physics, but also in technological areas of communication by capitalizing on unconventional valley-Hall physics.