Observation of Acoustic Valley Vortex States and Valley-Chirality Locked Beam Splitting
arXiv:1612.08602 · doi:10.1103/PhysRevB.95.174106
Abstract
The Letter reports an experimental observation of the classical version of valley polarized states in a two-dimensional hexagonal sonic crystal, where the inversion-symmetry breaking of scatterers induces an omnidirectional frequency gap. The acoustic valley states, which carry specific linear momenta and orbital angular momenta, were selectively excited by external Gaussian beams and conveniently confirmed by the pressure distribution outside the crystal, according to the criterion of momentum conservation. The vortex nature of such intriguing crystal states was directly characterized by scanning the phase profile inside the crystal. In addition, we observed a peculiar beam splitting phenomenon, in which the separated beams are constructed by different valleys and locked to the opposite vortex chirality. The exceptional sound transport, encoded with valley-chirality locked information, may serve as the basis of designing conceptually novel acoustic devices with unconventional functions.
12 pages and 4 figures, experimental study
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Cited by in corpus (28)
- Topological acoustics
- Direct Observation of Valley-polarized Topological Edge States in Designer Surface Plasmon Crystals
- Topological Sound
- Observation of topological valley modes in an elastic hexagonal lattice
- Valley Topological Phases in Bilayer Sonic Crystals
- Artificial gauge fields in materials and engineered systems
- Topological phononic insulator with robustly pseudospin-dependent transport
- Snowflake Topological Insulator for Sound Waves
- Tunable light flow control in valley photonic crystal waveguide
- Observation of Gigahertz Topological Valley Hall Effect in Nanoelectromechanical Phononic Crystals
- Designing multi-directional energy-splitters and topological valley supernetworks
- Observation of topological edge states of sound at a momentum away from the high-symmetry point
- Acoustic Dirac degeneracy and topological phase transitions realized by rotating scatterers
- Valley-projected edge modes observed in underwater sonic crystals
- Elastic Valley Spin Controlled Chiral Coupling in Topological Valley Phononic Crystals
- Valley Hall phases in Kagome lattices
- Tracking valley topology with synthetic Weyl paths
- Valley Anisotropy in Elastic Metamaterials
- Valley vortex states and degeneracy lifting via photonic higher-band excitation
- Hybrid topological guiding mechanisms for photonic crystal fibers
- Guiding Robust Valley-dependent Edge States by Surface Acoustic Waves
- Higher-order topological spin Hall effect of sound
- Observations of symmetry induced topological mode steering in a reconfigurable elastic plate
- Experimental observations of topologically guided water waves within non-hexagonal structures
- Tunable three-way valley Hall energy-splitter: venturing beyond graphene-like structures
- Structure-Composition Correspondence in Crystalline Metamaterials for Acoustic Valley-Hall Effect and Unidirectional Sound Guiding
- Properties of the eigenmodes and quantum-chaotic scattering in a superconducting microwave Dirac billiard with threefold rotational symmetry
- Acoustic topological circuitry in square and rectangular phononic crystals