  We study how an optical parametric amplifier inside the cavity can affect the
normal mode splitting behavior of the coupled movable mirror and the cavity
field. We work in the resolved sideband regime. The spectra exhibit a
double-peak structure as the parametric gain is increased. Moreover, for a
fixed parametric gain, the double-peak structure of the spectrum is more
pronounced with increasing the input laser power. We give results for mode
splitting. The widths of the split lines are sensitive to parametric gain.
