Rotational manipulation by acoustic radiation torque of high-order vortex beams generated by an artificial structured plate

Abstract

As a nondestructive and contactless method of rotational manipulation on objects, acoustic radiation torque has attracted much attention in recent years. Here, we propose an effective way to generate high-order acoustic vortex beams simply by a structured plate and demonstrate flexible rotational manipulations on objects with different shapes such as disks or small balls or sticks by the generated vortex beams. Two structural plates carved with one set or two sets of Archimedean spiral gratings on a single side are fabricated to get the first-order and second-order acoustic vortex beams at the same frequency, respectively, acoustic radiation torque of which is experimentally analyzed through the rotational manipulation of a standard acoustic absorption disk. Furthermore, we extend the rotational manipulation on different objects such as small balls and sticks, which gives an intuitive picture of angular momentum transfer from vortex beams to absorption materials. We believe that the present work will pave a way to potential applications in acoustic and biomedical fields.