Three-Dimensional Acoustic Double-Zero-Index Medium with a Fourfold Degenerate Dirac-like Point

Changqing Xu, Guancong MA, Ze Guo Chen, Jie Luo, Jinjie Shi, Yun Lai, Ying Wu

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

We report the first realization of a three-dimensional (3D) acoustic double-zero-index medium (DZIM) made of a cubic lattice of metal rods. While the past decade has seen several realizations of 2D DZIM, achieving such a medium in 3D has remained an elusive challenge. Here, we show how a fourfold degenerate point with conical dispersion can be induced at the Brillouin zone center, such that the material becomes a 3D DZIM with the effective mass density and compressibility simultaneously acquiring near-zero values. To demonstrate the functionalities of this new medium, we have fabricated an acoustic waveguide of 3D DZIM in form of a "periscope" with two 90° turns and observed tunneling of a normally incident planar wave through the waveguide yielding undistorted planar wave front at the waveguide exit. Our findings establish a practical route to realize 3D DZIM as an effective acoustic "void space" that offers unprecedented control over acoustic wave propagation.

Original languageEnglish
Article number074501
JournalPhysical Review Letters
Volume124
Issue number7
DOIs
Publication statusPublished - 19 Feb 2020

Scopus Subject Areas

  • Physics and Astronomy(all)

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