Convert Acoustic Resonances to Orbital Angular Momentum.

Area of Science:

• Acoustics
• Wave Physics
• Optics (analogous principles)

Background:

• Generating vortex beams with orbital angular momentum (OAM) is crucial for advanced wave manipulation.
• Existing methods often rely on complex phased arrays or intricate spiral surface profiles.

Purpose of the Study:

• To introduce a simpler and more efficient method for producing acoustic vortex beams with OAM.
• To demonstrate the generation of airborne Bessel-like vortex beams using acoustic resonances.

Main Methods:

• Utilizing acoustic resonances within a planar layer of half-wavelength thickness.
• Employing this mechanism to twist the wave vectors of incoming plane waves.
• Numerical and experimental validation of the proposed method.

Main Results:

• Successfully generated an airborne Bessel-like vortex beam with OAM.
• Demonstrated the twisting of plane wave vectors into spiral phase dislocations.
• The acoustic resonance method offers an alternative to elaborate OAM generation techniques.

Conclusions:

• Acoustic resonances provide an effective mechanism for OAM production in acoustic waves.
• This study advances the capability for generating phase-dislocated wave fields.
• The findings have potential implications for future applications of acoustic OAM.