  We propose a scheme that can generate a tunable double optomechanically
induced transparency (OMIT) in a hybrid optomechanical cavity system, in which
the mechanical resonator of an optomechanical cavity is coupled to an
additional mechanical resonator, and the additional mechanical resonator can be
driven by a weak external coherently mechanical driving field. We show that
both the intensity and the phase of the the external mechanical driving field
can control the propagation of the probe field, including changing the
transmission spectrum curve from a double-window to a single-window. Our study
also provides an effective way to produce an intensity-controllable
narrow-bandwidth transmission spectra, with the probe field modulated from
excessive opacity to remarkable amplification.
