Acoustic Bessel Vortex Beam by Quasi-Three-Dimensional Reflected Metasurfaces

Area of Science:

• Acoustics
• Metamaterials
• Wave physics

Background:

• Acoustic vortex beams possess orbital angular momentum, enabling applications in communication and particle manipulation.
• Acoustic vortex beams typically diffuse easily in free space, limiting their propagation distance.
• Previous realizations often required metamaterial surfaces or waveguides, hindering free-space applications.

Purpose of the Study:

• To overcome the challenge of long-distance free-space propagation for acoustic vortex beams.
• To introduce a novel acoustic Bessel vortex (ABV) beam.
• To demonstrate the high performance and broad bandwidth of the proposed ABV beam.

Main Methods:

• Utilizing a quasi-three-dimensional reflected metasurface.
• Employing phase modulation based on Bessel and vortex phase profiles.
• Creating an acoustic Bessel vortex (ABV) beam in free space.

Main Results:

• The developed ABV beam exhibits effective propagation exceeding 9.2 wavelengths in free space.
• The fractional bandwidth of the ABV beam reaches approximately 0.28.
• The study successfully demonstrates a high-performance vortex beam with extended propagation and broad bandwidth.

Conclusions:

• The proposed acoustic Bessel vortex (ABV) beam offers a promising solution for long-distance acoustic vortex propagation in free space.
• The metasurface-based approach enables multifunctional vortex devices with enhanced performance.
• This work opens new avenues for advanced applications in acoustic communication and non-contact manipulation.