Disorder effect on the focus image of sonic crystals in air

Abstract

When acoustic waves propagate in two-dimensional sonic crystals composed of parallel rigid cylinders in air, anisotropic band gaps, such as a partial gap and deaf band, forbid the waves within certain frequency regions from propagating along certain directions, thus forming a stable imaging focus effect. If the introduced disorder has not destroyed the original anisotropic band gap, this unique effect still exists, although the focused image becomes blurred. Once the sample reaches complete disorder, the anisotropic band gap is destroyed, and this effect also disappears.