Phononic crystals operating in the gigahertz range with extremely wide band gaps

Abstract

Phononic crystals have numerous potential applications including use as filters and oscillators in communications systems and as acoustic isolators for resonant sensors such as gyroscopes. These applications are based on the ability of phononic crystals to exhibit elastic band gaps, frequency bands where the propagation of acoustic waves is forbidden. Here, we focus on solid-solid phononic crystals (solid inclusions in a solid matrix), since they typically exhibit wider band gaps than those observed with air-solid phononic crystals (air inclusions in a solid matrix). We present a micromachined solid-solid phononic crystal operating at 1.4 GHz center frequency with an ultrawide 800 MHz band gap.