Phononic band-gap crystals for radio frequency communications

We report on the experimental and theoretical observation of a phononic band-gap crystal operating in the megahertz regime. Our experimental data show over 25 dB suppression of bulk acoustic waves, and our theoretical models predict almost linear scaling to the gigahertz frequencies, thus laying the foundation for the implementation of such devices in radio frequency communications. We further argue that cavities in such systems offer a unique opportunity to couple acoustic energy into a resonator utilizing piezoelectric materials, while at the same time allowing the realization of a resonance cavity in high- Q materials such as silicon oxide, silicon, and tungsten.