Membrane-based acoustic metamaterial with near-zero refractive index

• Published in: Chinese physics B 2017, Vol.26 (1), p.237-242
• Main Author: 李义丰 蓝君 余辉洋 刘晓宙 张嘉澍
• Format: Article
• Language: English
• Subjects: 共振频率; 声传输; 声学; 声能量; 弹性膜; 折射率; 材料连接; 波导管
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/26/1/014302

We investigate a one-dimensional acoustic metamaterial with a refractive index of near zero（RINZ） using an array of very thin elastic membranes located along a narrow waveguide pipe. The characteristics of the effective density, refractive index, and phase velocity of the metamaterial indicate that, at the resonant frequency fm, the metamaterial has zero mass density and a phase transmission that is nearly uniform. We present a mechanism for dramatic acoustic energy squeezing and anomalous acoustic transmission by connecting the metamaterial to a normal waveguide with a larger cross-section. It is shown that at a specific frequency f1, transmission enhancement and energy squeezing are achieved despite the strong geometrical mismatch between the metamaterial and the normal waveguide. Moreover, to confirm the energy transfer properties, the acoustic pressure distribution, acoustic wave reflection coefficient, and energy transmission coefficient are also calculated. These results prove that the RINZ metamaterial provides a new design method for acoustic energy squeezing,super coupling, wave front transformation, and acoustic wave filtering.