Asymmetric propagation using enhanced self-demodulation in a chirped phononiccrystal

Asymmetric propagation of acoustic waves is theoretically reported in a chirped phononic crystalmade of the combination of two different nonlinear solids. The dispersion of the system is spatially dependentand allows the rainbow trapping inside the structure. Nonlinearity is used to activate theself-demodulation effect, which is enhanced due to the particular dispersioncharacteristics of the system. The performed numerical study reveals an efficient generationof the demodulated wave, up to 15% in terms of the pressure amplitude, as well as strongattenuation for undesired frequency components above the cut-off frequency. The obtainedenergy rectification ratio is in the order of 104 for the wholerange of amplitudes employed in this work, indicating the robustness of the asymmetry andnon-reciprocity of the proposed device for a wide operational range.