Multi-channel waveguides based on two dimensional phononic crystals

Using supercell plane wave method, we investigated defect modes created by introducing two types of defect with multi-branch in a two dimensional acoustic band-gap material consisting of water cylinders in mercury background. The defect is made up of the water cylinders with different size, and the size of the defect cylinders are 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 defect. It provides us a foundation in theory to design multi-channel waveguide in engineering application.