  We describe the strong optomechanical dynamical interactions in ultrahigh-Q/V
slot-type photonic crystal cavities. The dispersive coupling is based on a
mode-gap photonic crystal cavities with light localization in an air mode with
0.02(lambda/n)3 modal volumes while preserving optical cavity Q up to 5 x 106.
The mechanical mode is modeled to have fundamental resonance omega_m/2pi of 460
MHz and a quality factor Qm estimated at 12,000. For this slot-type
optomechanical cavity, the dispersive coupling gom is numerically computed at
up to 940 GHz/nm (Lom of 202 nm) for the fundamental optomechanical mode.
Dynamical parametric oscillations for both cooling and amplification, in the
resolved and unresolved sideband limit, are examined numerically, along with
the displacement spectral density and cooling rates for the various operating
parameters.
