microparticles) and plays an important role such as in biomedical applications 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the OAM-based multiplexing and de-multiplexing mechanism offers new route to boost the capacity of acoustic communication 13, 14. For instance, the orbital angular momentum (OAM) transfer from acoustic vortex beams to matter allows nondestructive and contactless manipulation on tiny objects (e.g. The past few years witness considerable efforts devoted to both theoretical and experimental study on acoustic vortices due to the fundamental interest and practical importance of their unconventional characteristics such as null pressure amplitude at the core 1 and spiral phase dislocations 2. We anticipate our design with simplicity, compactness, precision and flexibility to open up possibility to design novel vortex devices and find important applications in diverse scenarios such as on-chip particle manipulations. The performance of our strategy is demonstrated via precise production of different orders of non-aliased vortices regardless of center-to-center alignment, with undistorted Bessel-like pattern extending to the whole inner region. We derive the criterion on unit size for eliminating spatial aliasing effect which is challenging for conventional active approaches and design a membrane-based metasurface to implement our mechanism. We propose to generate 2D acoustic vortex inside an enclosed metasurface illuminated by axisymmetric wave carrying no orbital angular momentum.
Two-dimensional (2D) acoustic vortex allows new physics and applications different from three-dimensional counterparts, yet existing mechanisms usually have to rely on active array composed of transducers which may result in complexity, high cost and, in particular, undesired spatial aliasing effect.
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