Defect states in 2D acoustic band-gap materials with bend-shaped linear defects

Using the supercell plane wave method, we investigated defect modes created by introducing a bend-shaped linear defect in a two-dimensional acoustic band-gap material consisting of water cylinders in mercury background. The bend-shaped linear defect is made up of the water cylinders with different size, and the size of the defect cylinders is shown to strongly influence the defect modes existing in the frequency regime of the gap. By analyzing the pressure field of defect modes, we found the waves are localized in the bend-shaped linear defect. It provides us a foundation in theory to design a bent waveguide in engineering application.