Meta-atom cluster acoustic metamaterial with broadband negative effective mass density

Abstract

We design a resonant meta-atom cluster, via which a two-dimensional (2D) acoustic metamaterial (AM) with broadband negative effective mass density from 1560 Hz to 5580 Hz is fabricated. Experimental results confirm that there is only weak interaction among the meta-atoms in the cluster. And then the meta-atoms in the cluster independently resonate, resulting in the cluster becoming equivalent to a broadband resonance unit. Extracted effective refractive indices from reflection and transmission measurements of the 2D AM appear to be negative from 1500 Hz to 5480 Hz. The broadband negative refraction has also been demonstrated by our further experiments. We expect that this meta-atom cluster AM will significantly contribute to the design of broadband negative effective mass density AM.

Manipulation of transmitted wave front using ultrathin planar acoustic metasurfaces

“…Besides, the fabrication of gradient index lens is relatively complicated, and they can only realize limited phase shifts. Recent investigations in metamaterials have opened up new avenues for manufacturing various novel devices [6][7][8][9][10][11][12][13], in which the electromagnetic metasurface as a new approach has attracted tremendous interests of researchers [14][15][16][17][18][19]. The arbitrary modulation of electromagnetic waves could be realized just via ultrathin artificial composite materials, including bending of the direction of propagating waves, abnormal transmission and reflection, and planar lenses.…”

Negative refraction realized by band folding effect in resonator-based acoustic metamaterials

“…As a natural extension, a double negative AM (DNAM) has been constructed by combining these two kinds of resonators in one structure [12,[18][19][20][21][22][23]. However, because the commonly suggested dipolar and monopolar resonators are realized respectively by the rubber-coated heavy mass in solid and the Helmholtz resonator in fluid, their combination usually leads to a mixture of solid and fluid materials [18], which makes the whole structure very complicated.…”

Effective Negative Mass Nonlinear Acoustic Metamaterial with Pure Cubic Oscillator

“…Yao et al [26] realized effective negative mass and zero-mass phenomena in a 1D mass-spring system experimentally. Other different types of acoustic metamaterials with negative effective mass have been proposed [27][28][29][30][31][32]. From the existing literatures, the starting frequency bandgap of metamaterials is defined by local resonance frequency where the effective negative mass just began.…”