title: Implementation of dispersion-free slow acoustic wave propagation and phase engineering with helical-structured metamaterials.
abstract: The ability to slow down wave propagation in materials has attracted significant research interest. A successful solution will give rise to manageable enhanced wave-matter interaction, freewheeling phase engineering and spatial compression of wave signals. The existing methods are typically associated with constructing dispersive materials or structures with local resonators, thus resulting in unavoidable distortion of waveforms. Here we show that, with helical-structured acoustic metamaterials, it is now possible to implement dispersion-free sound deceleration. The helical-structured metamaterials present a non-dispersive high effective refractive index that is tunable through adjusting the helicity of structures, while the wavefront revolution plays a dominant role in reducing the group velocity. Finally, we numerically and experimentally demonstrate that the helical-structured metamaterials with designed inhomogeneous unit cells can turn a normally incident plane wave into a self-accelerating beam on the prescribed parabolic trajectory. The helical-structured metamaterials will have profound impact to applications in explorations of slow wave physics.
authors.affiliation: College of Physical Science and Technology, Heilongjiang University, Harbin 150080, China.|Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, China.|Innovation Institute, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Zhu
authors.affiliation: College of Physical Science and Technology, Heilongjiang University, Harbin 150080, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.affiliation: State Key Laboratory of Transient Optics and Photonics, Chinese Academy of Sciences, Xi'an 710119, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Mechanical Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
authors.forename: Jie
authors.identifier: 0000-0001-9432-2892
authors.initials: J
authors.lastname: Zhu
authors.affiliation: College of Physical Science and Technology, Heilongjiang University, Harbin 150080, China.
authors.forename: Jintao
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor Michigan 48109, USA.
authors.forename: Chao
authors.initials: C
authors.lastname: Tian
authors.affiliation: College of Physical Science and Technology, Heilongjiang University, Harbin 150080, China.|Department of Biomedical Engineering, University of Michigan, Ann Arbor Michigan 48109, USA.
authors.forename: Shengchun
authors.initials: S
authors.lastname: Liu