Acoustic response in a one-dimensional layered pseudo-Hermitian metamaterial containing defects

作者：Psiachos D^*; Sigalas M M^*

来源：Journal of Applied Physics, 2018, 123(24): 245109.

DOI：10.1063/1.5027457

Using transfer-matrix methods, we investigate the response of a multilayered metamaterial system containing defects to an incident acoustic plane wave at normal or oblique incidence. The transmission response is composed of pass-bands with oscillatory behaviour, separated by band gaps, and covers a wide frequency range. The presence of gain and loss in the layers leads to the emergence of symmetry breaking and re-entrant phases. In the general case, a system containing defects will display a more general property, pseudo-Hermiticity (PH), of which PT systems are a subset. In the PH-symmetric phase, unidirectional responses of the reflection, accomplished by reversing the parity P, can be found, but the response sometimes deviates from the predictions of simple scattering theory which call for a pseudo-unitarity relation relating the transmission and the two directions of reflections to hold. The converse of reversing the parity and reversing the time operator T in a spatially asymmetric system within the PH-symmetric regime can lead to different transmissions: a pass-band versus a stop-band. As regions of stable PH-symmetric pass-band transmission oscillations occur over a wide spectral range, there is a large flexibility in system parameters such as layer thicknesses, for leading to the desired unidirectional traits. In addition, we find that while defects in general lead to a near or complete loss of PH symmetry at all frequencies, they can be exploited to produce highly sensitive responses, making such systems good candidates for sensor applications. Published by AIP Publishing.

• 出版日期2018-6-28