Layered and isotropic acoustic cloak design based on conformal transformation acoustics

The acoustic cloak can manipulate sound waves in surprising ways and enable us to guide the trajectories of waves at will. In contrast to the existing approaches for designing such devices that need exotic material parameters, here we demonstrate how to design a layered and isotropic acoustic cloak based on conformal transformation acoustics. A petal-shaped layered acoustic cloak is designed from the reduction of material parameters of an approximate rectangular cloak. The resultant material parameters span a narrow range, thus strongly facilitating the implementation. The invisibility performance of the cloak for different shapes of acoustic wavefront is verified using a full-wave finite-element analysis.