Frequency gaps and waveguiding in two-dimensional phononic plates with periodic stepped resonators

Phononic crystals are artificial periodic elastic structures that can generate acoustic frequency band gaps and maneuverable dispersion relations to control acoustic wave propagation. In this paper, we study the plate-mode acoustic wave propagation in a square array of stepped cylinders on an Al thin plate. We demonstrate the tunable band gap and waveguiding in the phononic structure with numerical calculations and laser ultrasonic measurements. Experimental results agree well with the numerical results. The band gaps, slow resonant waves, and waveguiding are observed.