  We develop an all-integrated optoelectromechanical system that operates in
the superhigh frequency band. This system is based on an ultrahigh-Q slotted
photonic crystal (PhC) nanocavity formed by two PhC membranes, one of which is
patterned with electrode and capacitively driven. The strong simultaneous
electromechanical and optomechanical interactions yield efficient electrical
excitation and sensitive optical transduction of the bulk acoustic modes of the
PhC membrane. These modes are identified up to a frequency of 4.20 GHz, with
their mechanical Q factors ranging from 240 to 1,730. Directly linking signals
in microwave and optical domains, such optoelectromechanical systems will find
applications in microwave photonics in addition to those that utilize the
electromechanical and optomechanical interactions separately.
