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

Area of Science:

• Acoustic Metamaterials
• Condensed Matter Physics
• Topological Physics

Background:

• Topological valley-contrasting physics utilizes the valley degree of freedom for information transfer.
• Previous acoustic topological states were limited by waveguide cut-off frequencies and lattice sizes.
• These limitations stem from topological edge states originating from Bragg interference.

Purpose of the Study:

• To engineer topologically valley-projected edge states in acoustic systems.
• To overcome the limitations of previous acoustic topological state demonstrations.
• To explore the potential for integrated acoustic devices based on valley physics.

Main Methods:

• Fabrication of a subwavelength honeycomb lattice using 330-mL soda cans.
• Engineering spoof surface acoustic waves for topological edge state confinement.
• Breaking inversion symmetry by introducing water into unit cell components to induce a topological valley-Hall phase transition.

Main Results:

• Demonstration of topologically valley-projected edge states confined along the lattice surface.
• Observation of dual-frequency ranges for valley-projected edge states below the sound line.
• Successful induction of a topological valley-Hall phase transition by breaking inversion symmetry.

Conclusions:

• The engineered acoustic system successfully exhibits topological valley-projected edge states.
• The results demonstrate a novel method for creating topological states in acoustic systems using readily available materials.
• This work opens avenues for designing advanced integrated acoustic devices leveraging valley-contrasting physics.