  This article presents the experimental characterization of nonreciprocal
elastic wave transmission in a single-mode elastic waveguide. This asymmetric
system is obtained by coupling a selection layer with a conversion layer: the
selection component is provided by a phononic crystal, while the conversion is
achieved by a nonlinear self-demodulation effect in a 3D unconsolidated
granular medium. A quantitative experimental study of this acoustic rectifier
indicates a high rectifying ratio, up to $10^6$, with wide band (10 kHz) and an
audible effect. Moreover, this system allows for wave-packet rectification and
extends the future applications of asymmetric systems.

Classical Physics