Symmetry selective directionality in near-field acoustics

Area of Science:

• Acoustics
• Wave Physics
• Metamaterials

Background:

• Controlling near-field evanescent waves is crucial for applications like communication and energy transfer.
• Understanding near-field symmetry and directional coupling, especially for longitudinal waves, remains a challenge.

Purpose of the Study:

• To explore the role of intrinsic geometry and symmetry in wave dynamics for near-field phenomena.
• To demonstrate efficient selective couplings of acoustic waves using near-field symmetry properties.

Main Methods:

• Utilized an acoustic wave platform to investigate near-field symmetry.
• Exploited inherent symmetry properties of orthogonal vectors in near-field acoustics.
• Experimentally demonstrated symmetry-selective directionality of evanescent modes using meta-surfaces.

Main Results:

• Successfully realized acoustic Janus, Huygens, spin, and quadrupole hybrid sources based on near-field symmetry.
• Demonstrated directional control of evanescent acoustic modes.
• Revealed near-field acoustic spin angular momentum properties through local vectorial field measurements.

Conclusions:

• Near-field symmetry properties are key to efficient selective wave couplings.
• The study provides feasible approaches for directional acoustic couplings.
• Findings pave the way for advanced acoustic devices leveraging near-field physics.