A phononic crystal can control the acoustic coupling between a resonator and its support structure. We micromachine a phononic bandgap shield for high Q silicon nitride membranes and study the driven displacement spectra of the membranes and their support structures. We find that inside observed bandgaps the density and amplitude of non-membrane modes are greatly suppressed, and membrane modes are shielded from an external mechanical drive by up to 30 dB.
@article{arxiv.1312.0962,
title = {A phononic bandgap shield for high-Q membrane microresonators},
author = {P. -L. Yu and K. Cicak and N. S. Kampel and Y. Tsaturyan and T. P. Purdy and R. W. Simmonds and C. A. Regal},
journal= {arXiv preprint arXiv:1312.0962},
year = {2015}
}