Tunable orbital angular momentum generator for directional acoustic transmission

Area of Science:

• Underwater acoustics
• Signal processing
• Optical physics (applied to acoustics)

Background:

• Underwater acoustic propagation is vital for detection, monitoring, and imaging due to low signal attenuation.
• Acoustic vortex (AV) communication, utilizing orbital angular momentum (OAM), aims to boost underwater data capacity.
• Precise directional control and signal focusing are essential for effective underwater AV communication.

Purpose of the Study:

• To present a novel scheme for actively tuning the propagation of acoustic vortex beams.
• To enhance the performance of OAM-based underwater communication systems through reconfigurable directional signal transmission.
• To address challenges in underwater communication, such as signal obstruction by obstacles.

Main Methods:

• Integration of two gradient lenses and a circular sawtooth lens with an active circular phased array.
• Generation of quasi-Bessel acoustic vortex beams.
• Active steering of the beam's central axis across a two-dimensional plane.

Main Results:

• Demonstration of active control over the transmission direction of acoustic vortex beams.
• Ability to transfer the beam's center to any desired 2D position.
• Achieved highly concentrated signals delivered to the target receiver's location.

Conclusions:

• The proposed method offers active adjustment of transmission direction for acoustic vortex beams.
• This approach provides lower costs and greater flexibility compared to traditional off-axis methods.
• The technology shows promising prospects for widespread applications in underwater acoustic communication.