  Optomechanical systems offer one of the most sensitive methods for detecting
mechanical motion using shifts in the optical resonance frequency of the
optomechanical resonator . Presently, these systems are used for measuring
mechanical thermal noise displacement or mechanical motion actuated by optical
forces. Electrostatic capacitive actuation and detection have been shown
previously for silicon micro electro mechanical resonators for application in
filters and oscillators. Here, we demonstrate monolithic integration of
electrostatic capacitive actuation with optical sensing using silicon
optomechanical disk resonators and waveguides. The electrically excited
mechanical motion is observed as an optical intensity modulation when the input
electrical signal is at a frequency of 235MHz corresponding to the radial
vibrational mode of the silicon microdisk.
