Guided Surface Acoustic Waves in Phononic Crystal Waveguides

In this paper, we adopt the finite-difference time-domain method to analyze surface acoustic waves propagating in two-dimensional phononic waveguides. A phononic crystal consisting of circular steel cylinders which form a square lattice in an epoxy matrix is considered as an example to study phononic crystal waveguides. The dispersion relation and displacement fields are calculated to identify the band gaps and eigenmodes. The result shows the existence of a complete band gap of surface waves and thus an acoustic waveguide is created accordingly. Eigenmodes of surface waves inside the waveguide are indicated and pseudo surface acoustic waves propagating inside the straight waveguide are demonstrated. Further, the waveguides with a sharp bend are reported and an improved design is suggested to enhance energy transmission.