Two-Dimensional Arbitrary Shape Acoustic Cloaks Composed of Homogeneous Parts Realized by Layered Structures

Acoustic cloaking is an important application of metamaterials and has received much attention since it was first proposed. Due to the extreme properties of the cloaks produced by previous methods, they are difficult to fabricate. In addition, cloaks with arbitrary shapes are more favorable in applications but are difficult to realize. Therefore, it is important to present a method for designing arbitrary shaped cloak with attainable properties. In this paper, a technique for realizing cloaks with arbitrary shapes is presented by dividing the cloak into finite parts. Transformation acoustics is used to derive the properties of each part of the cloak. With appropriate mapping relationships, the properties of each part are anisotropic but homogeneous. Layered structures are adopted to approximate the anisotropic properties within each part. Full wave simulations are conducted to validate this technique. The method can be used to design cloaks with arbitrary shapes, which perform well within certain frequency limits. It provides an easier way to fabricate cloaks with arbitrary shapes.