Acoustic metamaterials with broadband and wide-angle impedance matching

Chenkai Liu, Jie Luo, and Yun Lai

Phys. Rev. Materials 2, 045201 – Published 12 April 2018

Abstract

We propose a general approach to design broadband and wide-angle impedance-matched acoustic metamaterials. Such an unusual acoustic impedance matching characteristic can be well explained by using a spatially dispersive effective medium theory. For demonstrations, we used silicone rubber, which has a huge impedance contrast with water, to design one- and two-dimensional acoustic structures which are almost perfectly impedance matched to water for a wide range of incident angles and in a broad frequency band. Our work opens up an approach to realize extraordinary acoustic impedance matching properties via metamaterial-design techniques.

Received 13 October 2017

DOI:https://doi.org/10.1103/PhysRevMaterials.2.045201

Physics Subject Headings (PhySH)

Acoustic metamaterials Acoustic wave phenomena

General Physics

Authors & Affiliations

Chenkai Liu¹, Jie Luo^1,*, and Yun Lai^2,1,*

¹College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, China
²National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China

^*Corresponding authors: luojie@suda.edu.cn; laiyun@nju.edu.cn

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 2, Iss. 4 — April 2018

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) Illustration of the 1D impedance-matched AMM. (b) Band structure of the 1D AMM. The red dashed line denotes the central frequency ${f a / c}_{w} = 0.335$ . The inset shows the illustration of the unit cell. (c) EFC of the second band. The red and blue dashed lines denote the EFCs of the AMM and water, respectively, at ${f a / c}_{w} = 0.335$ . (d) Impedance difference between the AMM and water. (e) Effective parameters $ρ_{eff}$ and $κ_{eff}$ of the 1D AMM from Eq. (4) (symbols) and from Eq. (3) (dotted lines).
Reuse & Permissions
Figure 2
Incident angle-dependent transmittance for acoustic waves propagating through (a) the 1D AMM slab composed of $n (= 4$ , 5, 6, 15) unit cells, and (b) combined silicone rubber slab with for the cases of $n = 4$ and $n = 15$ at the frequency ${f a / c}_{w} = 0.335$ . The insets show the numerical setups for the transmission computation. Transmittance as functions of the incident angle and the frequency for acoustic waves propagating through (c) the 1D AMM slab with 15 unit cells, and (d) the combined silicone rubber slab.
Reuse & Permissions
Figure 3
(a) Illustration of 2D impedance-matched AMM. (b) Band structure of the 2D AMM. The red dashed line denotes the central frequency ${f a / c}_{w} = 0.357$ . The inset shows the illustration of the unit cell. (c) The EFC of the third band. The red and blue dashed lines denote the EFCs of the AMM and water at ${f a / c}_{w} = 0.357$ , respectively. (d) Impedance difference between the AMM and water. (e) Effective parameters $ρ_{eff}$ and $κ_{eff}$ of the 2D AMM from Eq. (4) (symbols) and from Eq. (3) (dotted lines).
Reuse & Permissions
Figure 4
Incident-angle-dependent transmittance for acoustic waves propagating through (a) 2D AMM slab composed of $n (= 4$ , 5, 6, 15) unit cells, and (b) combined silicone rubber slab with for the cases of $n = 4$ and $n = 15$ at the frequency ${f a / c}_{w} = 0.357$ . The insets show the numerical setups for the transmission computation. Transmittance as functions of the incident angle and the frequency for acoustic waves propagating through (c) 2D AMM slab with 15 unit cells, and (d) combined silicone rubber slab.
Reuse & Permissions
Figure 5
Incident-angle-dependent transmittance for acoustic waves propagating through (a) 1D AMM slab composed of $n (= 4$ , 15) unit cells at the frequency ${f a / c}_{w} = 0.335$ , and (b) 2D AMM slab composed of $n (= 4$ , 15) unit cells at the frequency ${f a / c}_{w} = 0.357$ . The solid lines denote the acoustic-structure model by taking the shear modulus into account and the symbols denote the acoustic model without considering the shear modulus. The insets show the numerical setups for the transmission computation. Transmittance as functions of the incident angle and the ratio of the shear velocity to the longitudinal velocity for acoustic waves propagating through (c) 1D AMM slab with 15 unit cells, and (d) 2D AMM slab with 15 unit cells.
Reuse & Permissions
Figure 6
(a) Transmittance, reflectance and, absorbance as a function of incident angle through the designed 1D AMM composed of $n = 4$ unit cells with an imaginary part of 1% in the bulk modulus of silicone rubber. (b) Absorbance and (c) reflectance as a function of the imaginary part of the modulus of the silicone rubber and of the incident angle.
Reuse & Permissions

Physical Review Materials