Observation of acoustic Dirac-like cone and double zero refractive index

• DOI: 10.1038/ncomms14871
• Publication Date: 2017-03-20T09:59:39Z
• Authors: Marc Dubois; Chengzhi Shi; Xuefeng Zhu; Yuan Wang; Xiang Zhang
• Keywords: Brillouin zone; Waveguide

Abstract Zero index materials where sound propagates without phase variation, holds a great potential for wavefront and dispersion engineering. Recently explored electromagnetic double zero metamaterials consist of periodic scatterers whose refractive is significantly larger than that the surrounding medium. This requirement fundamentally challenging airborne acoustics because speed (inversely proportional to index) in air among slowest. Here, we report first experimental realization an impedance matched acoustic metamaterial induced by Dirac-like cone at Brillouin zone centre. achieved two-dimensional waveguide with periodically varying channel modulates effective velocity high-order mode. Using such zero-index medium, demonstrated wave collimation emitted from point source. For time, experimentally confirm existence