Acoustic vortices: production, manipulation and application of acoustic rbital angular momentum

vortices with spiral phase dislocations have recently attracted considerable attention due to the theoretical and application importance of their orbital angular momentum(OAM). The transfer of acoustic OAM to matter produces a torque that can trap and rotate tiny objects contactlessly, with deep implications in applications such as particle manipulation. Acoustic vortices have been traditionally generated by active methods in need of phased arrays comprising a large number of individually addressed transducers or by passive materials with spatially-varying thickness and spiral structures, which may limit their potential in practical applications. Lately, a resonance-based production of acoustic OAM devices has been proposed and experimentally demonstrated which offers a solution with high efficiency, compact size and planar profile. Even more recently, the application of acoustic OAM has been extended to open a new approach for multiplexing and de-multiplexing to boost high-capacity acoustic communication. This article will present a comprehensive overview of the recent advances in the production, manipulation and application of acoustic OAM-carrying vortex beams.