Ultrathin Acoustic Holography

How to realize acoustic holography via ultradeep-subwavelength structures is a challenging problem in the past decades, which is thought impossible due to the linear proportional relationship between the structural thickness and acoustic wavelength. In this article, the methodology of ultrathin holography by patterning holes in an acoustic insulation plate with an ultradeep-subwavelength thickness is introduced. The transmitted sound field can be manipulated arbitrarily to form a desired shape by designing the ultrathin pattern based on the nonlocal wave interaction theory. The physical mechanism of the nonlocal behavior to achieve a sophisticated hologram is revealed due to the interaction among the sound wave components themselves. Furthermore, the experiments are designed to map out the pressure amplitude field of a "sun" pattern in air and water, respectively. The work demonstrates the advantage of nonlocal ultrathin holography in the applications of ultrathin acoustic devices and provides inspiration for the holographic wave manipulation.