Asymmetric acoustic retroflection with a non-Hermitian metasurface mirror

We proposed and designed a non-Hermitian metasurface mirror consisting of two-layers acoustic labyrinthine metamaterials with a full phase control and inherent loss. It yields strongly asymmetric acoustic retroflection (>35 dB) for two opposite incident angles: free retroflection for positive incidence (PI) and strong absorption for negative incidence (NI). It is due to the different diffraction orders related to the period grating for two opposite incident angles: the value of 0 (without multiple reflections) for PI and the value of 2 (with multiple reflections) for NI. Our design may have prospective applications in acoustic sensing, acoustic antennas and noise control.

Automated summary

Our proposed non-Hermitian metasurface mirror, made of two-layers acoustic labyrinthine metamaterials, achieves full phase control and asymmetric acoustic retroflection for positive and negative incidence angles. The design shows potential applications in acoustic sensing, acoustic antennas, and noise control.