Unidirectional invisibility of an acoustic multilayered medium with parity-time-symmetric impedance modulation

Shuowei An, Tuo Liu, Shanjun Liang, He Gao, Zhongming Gu, Jie Zhu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Non-Hermitian scattering systems respecting parity-time symmetry exhibit unidirectional invisibility or reflectionlessness at an exceptional point of the scattering matrix. In this study, we investigate the scattering properties of a one-dimensional acoustic parity-time-symmetric multilayered medium. Parity-time symmetry is defined by a spatial small-amplitude square-wave modulation of the medium parameters in the complex plane. Such a multilayered medium has been demonstrated to reach an exceptional point and support unidirectional invisibility for balanced real and imaginary part modulations of the refractive index. Through the analysis of interference within the medium, we show that the complex modulation of acoustic impedance instead of the refractive index governs the exceptional point of the scattering matrix and determines the occurrence of the unidirectional invisibility. This unidirectional invisibility is further investigated for more general cases of complex parameter distribution including unequal modulation amplitudes and rectangular wave modulation. Our study provides an intuitive physical picture of the occurrence of unidirectional invisibility induced by an exceptional point in acoustic wave systems. Moreover, this study could facilitate the design and practical realization of acoustic parity-time-symmetric structures.

Original languageEnglish
Article number175106
JournalJournal of Applied Physics
Volume129
Issue number17
DOIs
Publication statusPublished - 7 May 2021

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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