A Mode-Matching Approach for Acoustic Vortex Generation in Circular Array Configurations

Acoustic vortices carrying orbital angular momentum (OAM) have great potential in underwater communication for improving the communication rate. However, generating high-quality acoustic vortices using a sonar array remains a challenge. The mode-matching approach is an effective way to reconstruct a desired acoustic field within a closed array. In this letter, we propose a mode-matching approach for any acoustic vortex fields using a planar circular array, including uniform and non-uniform arrays, with spherical harmonic expansion. The derivation of formulation to calculate the array driving function is given and numerical simulation is performed. We analyzed the influence of selecting the truncation order and the results indicate that using a finite truncation order to synthesize the acoustic vortex field is feasible. In addition, the simulation results of our proposed approach show that the generated acoustic vortex field has higher accuracy in both uniform circular array (UCA) and non-uniform circular array (NUCA) scenarios than the traditional method.