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Acoustic Orbital Angular Momentum Hall Effect at Metasurfaces
Xinyue Gong1, Joao L Ealo1,2, Likun Zhang1
1University of Mississippi, National Center for Physical Acoustics and Department of Physics and Astronomy, University, Mississippi 38677, USA.
Physical Review Letters
|March 20, 2026
Summary
Researchers observed the acoustic orbital Hall effect using airborne vortex beams. This study measures extrinsic orbital angular momentum (OAM) and reveals new insights into acoustic Hall phenomena and metasurface applications.
Area of Science:
- Acoustics
- Metasurfaces
- Quantum Optics
Background:
- Orbital angular momentum (OAM) plays a crucial role in wave phenomena.
- Metasurfaces offer novel ways to manipulate wave properties.
- Acoustic Hall effects are less explored compared to optical counterparts.
Purpose of the Study:
- To experimentally observe and characterize the acoustic orbital Hall effect.
- To investigate the role of extrinsic orbital angular momentum (OAM) in acoustic metasurfaces.
- To establish a framework for acoustic Hall effect measurements.
Main Methods:
- Generation of airborne vortex beams using a four-speaker source.
- Direct experimental measurement of Hall-induced extrinsic OAM.
- Field decomposition for analyzing energy flow and angular momentum symmetry.
Main Results:
- First direct experimental observation of the acoustic orbital Hall effect at metasurfaces.
- Measurement of twist-dependent Imbert-Fedorov shifts as a signature of extrinsic OAM.
- Observation of coexisting transverse energy flow and reconstructed axial angular-momentum symmetry.
- Detection of a geometric Hall effect in the tilted refracted beam.
Conclusions:
- The study provides a novel framework for measuring and interpreting acoustic Hall phenomena.
- Findings offer insights into extrinsic and intrinsic OAM in realistic acoustic systems.
- Advances potential applications in OAM-metasurface technology.
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