Phononic crystal waveguides for electromechanical circuits

Nanoelectromechanical systems (NEMS), utilising localised mechanical vibrations, were pioneered for sensors, signal processors and to study macroscopic quantum mechanics. Increasingly the concept of integrating multiple mechanical elements via electrical/optical means has emerged as a challenge towards NEMS circuits. Here we develop phononic crystal waveguides (PnC WGs), using a 1-dimensional array of suspended membranes, that offer purely mechanical means to integrate isolated NEMS resonators. In the first steps to this objective, we demonstrate the PnC WG can support and guide mechanical vibrations where the periodic membrane arrangement also creates a phonon bandgap that enables the phonon propagation velocity to be controlled. Additionally embedding a phonon-cavity into the PnC allows mechanical vibrations in the WG to be dynamically switched or transferred to the cavity, illustrating the availability of WG-resonator coupling. These highly functional traits of the PnC WG architecture exhibit all the ingredients necessary to permit the realisation of all-phononic NEMS circuits.