Perfect Confinement of Acoustic Vortex by Phase-Gradient Metacage

Acoustic wave isolation and noise reduction are significant challenges in the fields of physics and various applications. Traditional noise-control devices are often hampered by substantial size limitations, and their operational efficacy is generally restricted to planar waveforms. In this study, we demonstrate perfect confinement of acoustic vortex waves using an acoustic metacage consisting of phase-gradient metasurfaces. By leveraging the parity-reversed diffraction rule of phase-gradient metasurfaces, the designed metacage exhibited remarkable capabilities for the perfect confinement of acoustic vortex waves, showing robust performance even in the presence of source offsets. These findings present a promising strategy for developing precise and adaptable acoustic confinement technologies.