An acoustic spatiotemporal vortex pulse generated by a reflective meta-grating

Abstract

Acoustic spatiotemporal vortex pulses (ASTVPs) with transverse orbital angular momentum (OAM) in the spatiotemporal domain have garnered increasing attention in recent years because they may present new avenues for OAM state applications. Here, we propose a simple reflective meta-grating (RMG) to efficiently produce an ASTVP in air. By harnessing the periodicity and mirror symmetry of the meta-grating, a phase singularity can be found at the resonance point in momentum-frequency domain. It is further demonstrated that the spiral phase in the momentum-frequency domain can be transferred to the spatiotemporal domain through Fourier transform, resulting in an ASTVP. In addition, the good robustness of the ASTVP against angular misalignment and structural defects in the meta-grating is presented‌ by finite-element method. Finally, the RMG is fabricated using 3D printing, and experimental results confirm the successful generation of the ASTVP by the RMG. Our work provides a simple strategy to achieve ASTVP and offers the possibility of using it for acoustic manipulation and acoustic communication.