Subwavelength Acoustic Valley-Hall Topological Insulators Using Soda Cans Honeycomb Lattices

Abstract

<jats:p>Topological valley-contrasting physics has attracted great attention in exploring the use of the valley degree of freedom as a promising carrier of information. Recently, this concept has been extended to acoustic systems to obtain nonbackscattering sound propagations. However, previous demonstrations are limited by the cut-off frequency of 2D waveguides and lattice-scale size restrictions since the topological edge states originate from Bragg interference. Here we engineer topologically valley-projected edge states in the form of spoof surface acoustic waves that confine along the surface of a subwavelength honeycomb lattice composed of 330-mL soda cans. The inversion symmetry is broken through injecting a certain amount of water into one of the two cans in each unit cell, which gaps the Dirac cone and ultimately leads to the topological valley-Hall phase transition. Dual-frequency ranges of the valley-projected edge states below the sound line are observed, which originate from the first-order and second-order resonances, respectively. These results have the potential to enable promising routes to design integrated acoustic devices based on valley-contrasting physics.</jats:p>

Manipulating topological valley modes in plasmonic metasurfaces

“…Previous plasmonic topological valley systems have solely focused on single band effects, but such a dual band structure allows topological valley states to exist in two frequency regimes. Dual band effects have also been demonstrated in photonic crystals [46] and acoustics [47].…”

Valley Hall Elastic Edge States in Locally Resonant Metamaterials

“…The third way to achieve elastic TIs is the breaking of spatial cell symmetry to realize the quantum valley Hall effect (QVHE) [29][30][31]. The QVHE system only requires the formation of a single Dirac degeneracy in the dispersion relation.…”

Acoustic suppressed topological refraction in valley sonic crystals

“…Inspired by it, researchers have extended the concept of valleytronics into acoustics [7][8][9][10][11][12][13][14][15][16][17][18]. Accompanied by the breaking of mirror [7][8][9][10][11][12][13] or inversion [15][16][17][18] symmetry, researchers have observed acoustic valley Hall (AVH) phase transitions, and demonstrated that there exist topological edge states [7][8][9][10][11][12][13][14][15][16][17][18][19][20] of sound in the domain walls between two valley sonic crystals (VSCs) with opposite valley Chern numbers. Beyond that, based on typical features of valley-momentum locking, the edge states have been demonstrated to support robust valley transports against various defects around the domain wall with negligible intervalley scatterings, which provides the feasibility of designing sound devices with versatile applications, such as valley selective sound transmitters [8], acoustic delay lines [11], energy concentrators [12], valley-chirality locked sound splitters [14], directional antennas [21], mode-conversion emitters…”

“…In the past few years, valleytronics has attracted great attentions in the fields of physics and microelectronics due to its potential applications in information processing, transport and communication [1][2][3][4][5][6]. Inspired by it, researchers have extended the concept of valleytronics into acoustics [7][8][9][10][11][12][13][14][15][16][17][18]. Accompanied by the breaking of mirror [7][8][9][10][11][12][13] or inversion [15][16][17][18] symmetry, researchers have observed acoustic valley Hall (AVH) phase transitions, and demonstrated that there exist topological edge states [7][8][9][10][11][12][13][14][15][16][17][18][19][20] of sound in the domain walls between two valley sonic crystals (VSCs) with opposite valley Chern numbers.…”