Band gap materials and micro-phononic devices

This paper presents simulation, design and fabrication of surface acoustic wave (SAW) and Lamb wave micro-phononic devices. To illustrate the band gap formation and possible applications, numerical simulations on the air/silicon phononic crystals (PCs) were conducted which include: surface acoustic waves (SAWs) in a half-space and Lamb waves in a plate. With a lattice constant of 20 µm and high filling fraction, complete band gaps in the range of hundred MHz were found. Based on the band gap properties, numerical simulations on the point defects, waveguides and cavities in PC plates were then performed and discussed. On the experimental side, the associated micro acoustic resonators for both SAW and Lamb waves are demonstrated. Results on the fabrication and measurements of the silicon based micro-PC devices in the hundred MHz ranges are encouraging and may find potential applications in the areas of wireless filters.