Realization of a phononic crystal operating at gigahertz frequencies

We report on the experimental realization of a phononic crystal, designed to operate at gigahertz frequencies. Detailed studies of the structure have been performed using finite difference time domain method to determine effects of slab modes in finite-thickness slabs, thus enabling precise guidance of experimental efforts. In particular, we find the slab mode effects mitigated in ultrathin (thickness less than lattice periodicity) and ultrathick (thickness more than ten times lattice periodicity) slabs. Gigahertz-frequency phononic crystals are well poised to find usage as high-Q resonators, waveguides, and coupling elements in a variety of application areas including RF communications.