Real-time simulations and experiments on ultrahigh frequency surface waves in micro-structured phononic crystals

We investigate experimentally and by numerical simulation the interaction between ultrahigh frequency surface acoustic waves (SAW) and periodic microstructures. We use both one-dimensional (1D) phononic crystals consisting of copper lines embedded in silicon oxide and 2D phononic crystals consisting of air-filled holes etched as a square lattice in a silicon substrate. Experimental results obtained by ultrashort pulsed optical excitation and interferometric detection are compared to time-domain finite element (FEM) simulations of the propagating ultrahigh frequency SAW with frequency components up to ~1 GHz in these phononic crystals, allowing the investigation of SAW scattering and phononic band structure. Good agreement was obtained between simulation and experiment.