Systematic design of multiplexed-acoustic-metasurface hologram with simultaneous amplitude and phase modulations

We propose a multiplexed-acoustic-metasurface hologram that can project multiple predesigned images at different frequencies. We demonstrate the generation of fourfold acoustic holographic images by one metasurface at 3500, 4500, 5500, and 6500 Hz, respectively, and discuss their fundamental physics. We uncover the design of this acoustic hologram which simultaneously realizes multiplexing and modulations of amplitude and phase. The proposed metasurface unit cell is composed of multiple acoustic resonant cavities leading to the multiplexing effect. We consider here both leaky and intrinsic losses, which provide simultaneous controllable manipulations of amplitude and phase. These proposed strategies significantly increase the degree of freedom of the classical metasurfaces, which may open up additional avenues for multifunctional compact acoustic devices.