Exploration of amphoteric and negative refraction imaging of acoustic sources via active metamaterials

Abstract

The present work describes the design of three flat superlens structures for acoustic source imaging and explores an active acoustic metamaterial (AAM) to realise such a design. The first two lenses are constructed via the coordinate transform method (CTM), and their constituent materials are anisotropic. The third lens consists of a material that has both a negative density and a negative bulk modulus. In these lenses, the quality of the images is “clear” and sharp; thus, the diffraction limit of classical lenses is overcome. Finally, a multi-control strategy is developed to achieve the desired parameters and to eliminate coupling effects in the AAM. • Effective acoustic medium can produce the characteristics of negative density and bulk modulus, or anisotropic density. • Negative refraction is induced in the acoustic metamaterials, i.e., the effective medium. • The flat superlenses made of the metamaterials can overcome some shortcomings of the conventional lenses. • Realisation the metamaterials for the superlenses with a multi-control strategy.