Optimization method to construct multiple acoustic vortices for holograms

Abstract

In this study, the novel optimization method of holograms based on spin density is developed by introducing a new degree of freedom—spin angular momentum density into the direct search method. This approach leverages the programmability of numerous pixels in holograms and eliminates the need for meticulous management of amplitude and phase at discrete points, facilitating the construction of multiple first-order acoustic vortices. We efficiently construct a pattern of 40 vortices within a plane and vortices with different intensities and structures using this approach. We also illustrate the practical application of our design methodology by showcasing its ability to manipulate particles through the transfer of angular momentum from vortices to particles. This work not only advances our understanding of acoustic vortices but also explore a new degree of freedom in designing holograms, potentially enhancing the capacity of holograms.