A gradient index sonic lens based on acoustic metamaterials

Abstract

We report a method to design and characterize broadband gradient index lenses. The lenses are based on two‐dimensional sonic crystals, which are periodic arrangements of elastic cylinders embedded in air. It will be shown that gradient index sonic lenses built with rigid cylinders are more powerful than conventionally curved lenses. We also demonstrate that the designing possibilities increased by considering the mixture of two types of cylinders in the sonic crystal. So, a gradient index lens with zero reflectance at the surface is proposed by employing a mixture of aerogel and rigid cylinders. Finally, a multiple scattering theory has been employed to compare the performance of conventionally curved lenses and gradient index lenses. [Work supported by MEC of Spain and GVA of Valencia.]