Bidirectional acoustic negative refraction based on a pair of metasurfaces with both local and global PT-symmetries

Jun Lan; Xiaowei Zhang; Liwei Wang; Yun Lai; Xiaozhou Liu

doi:10.1038/s41598-020-67793-x

Bidirectional acoustic negative refraction based on a pair of metasurfaces with both local and global PT-symmetries

Jun Lan, Xiaowei Zhang, Liwei Wang, Yun Lai^*, Xiaozhou Liu^*

^*Corresponding author for this work

Nanjing University

Research output: Contribution to journal › Article › peer-review

14 Citations (Scopus)

Abstract

Negative refraction plays an important role in acoustic wave manipulation and imaging. However, conventional systems based on acoustic metamaterials suffer from the limits induced by loss-related and resolution issues. In this work, a parity-time (PT)-symmetric system is introduced to realize loss-free bidirectional acoustic negative refraction. The system is composed of a pair of locally PT-symmetric multi-layer metasurfaces sandwiching a region of free space, which also forms a global PT symmetry. The property of bidirectional negative refraction, which is rare for general PT-symmetric structures, is related to the coexistence of amplification and absorption in the locally PT-symmetric metasurfaces at their PT-broken phases. Such metasurfaces can freely switch their states between coherent perfect absorber (CPA) and amplifier depending on the direction of incidence. Our results provide a physical mechanism for realizing bidirectional functions in acoustic PT-symmetric systems.

Original language	English
Article number	10794
Journal	Scientific Reports
Volume	10
Issue number	1
DOIs	https://doi.org/10.1038/s41598-020-67793-x
Publication status	Published - 1 Dec 2020
Externally published	Yes

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title = "Bidirectional acoustic negative refraction based on a pair of metasurfaces with both local and global PT-symmetries",

abstract = "Negative refraction plays an important role in acoustic wave manipulation and imaging. However, conventional systems based on acoustic metamaterials suffer from the limits induced by loss-related and resolution issues. In this work, a parity-time (PT)-symmetric system is introduced to realize loss-free bidirectional acoustic negative refraction. The system is composed of a pair of locally PT-symmetric multi-layer metasurfaces sandwiching a region of free space, which also forms a global PT symmetry. The property of bidirectional negative refraction, which is rare for general PT-symmetric structures, is related to the coexistence of amplification and absorption in the locally PT-symmetric metasurfaces at their PT-broken phases. Such metasurfaces can freely switch their states between coherent perfect absorber (CPA) and amplifier depending on the direction of incidence. Our results provide a physical mechanism for realizing bidirectional functions in acoustic PT-symmetric systems.",

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AU - Lai, Yun

AU - Liu, Xiaozhou

PY - 2020/12/1

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Bidirectional acoustic negative refraction based on a pair of metasurfaces with both local and global PT-symmetries

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