Hysteretic self-oscillatory acoustic radiation with tunable orbital angular momentum

Area of Science:

• Acoustics
• Nonlinear physics
• Quantum mechanics

Background:

• Vortex beams with orbital angular momentum (OAM) are crucial for particle manipulation and high-speed communication.
• Intracavity generation is an efficient method for producing high-quality OAM beams, but it's under-explored in acoustics.

Purpose of the Study:

• To propose and demonstrate a novel acoustic intracavity OAM generation mechanism.
• To achieve tunable topological charges in acoustic OAM beams.
• To explore the physics of nonlinear, non-Hermitian boundaries in acoustic resonators.

Main Methods:

• Utilized a compact resonator ring with a single nonreciprocal nonlinear boundary.
• Investigated the system in both linear and nonlinear regimes.
• Analyzed the non-Hermitian Zeeman-like effect and resonator locking phenomena.

Main Results:

• Demonstrated efficient acoustic intracavity OAM generation with tunable topological charges.
• Observed a non-Hermitian Zeeman-like effect in the linear regime, splitting eigenmodes.
• Achieved single-mode self-oscillatory OAM radiation with hysteresis and bistability in the nonlinear regime.

Conclusions:

• The proposed mechanism offers a new pathway for generating tunable acoustic OAM beams.
• The study reveals significant physics related to nonlinear, non-Hermitian boundaries.
• Paves the way for next-generation acoustic OAM sources, switchers, and memory devices.