Volume 132, Number 3, November 2020
|Number of page(s)||5|
|Section||Interdisciplinary Physics and Related Areas of Science and Technology|
|Published online||28 December 2020|
Subwavelength acoustic focusing within multi-breadth bands with a window-shape metasurface
Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University Changsha 410082, China
Received: 6 August 2020
Accepted: 21 October 2020
The traditional phase gradient acoustic focusing metasurfaces based on the generalized Snell law (GSL) can manipulate acoustic waves freely. However, their applications are limited largely because of their narrow bandwidth, large volume, and single function. To resolve these problems, a kind of window-shape acoustic focusing metasurface (WSAFM) is proposed, the well performed focusing can be obtained by the flexibly varied longitudinal length of two handles inside the basic structure unit (BSU). The results demonstrate that, within multi-breadth bands (5000 Hz –6500 Hz, 7100 Hz –7600 Hz, 12100 Hz –13600 Hz), the WSAFM can realize the near-zero–sidelobe (NZS) subwavelength focusing, the variation of focus position, and the breakthrough of diffraction limit at multi-frequency. More importantly, when the non-Hermitian parameters (non-Hermitian system) are introduced to the WSAFM, the focus intensity can be enhanced without varying other parameters. The WSAFM proposed in this paper shows promising potentials in biomedical ultrasound imaging and the design of acoustic devices with multi-breadth bands.
PACS: 81.05.Xj – Metamaterials for chiral, bianisotropic and other complex media / 43.20.+g – General linear acoustics / 78.67.Pt – Multilayers; superlattices; photonic structures; metamaterials
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