Parametric optomechanical oscillations in two-dimensional slot-type high-Q photonic crystal cavities

We experimentally demonstrate an optomechanical cavity based on an air-slot photonic crystal cavity with optical quality factor Q(o) - 4.2 x 10(4) and a small modal volume of 0.05 cubic wavelengths. The optical mode is coupled with the in-plane mechanical modes with frequencies up to hundreds of MHz. The fundamental mechanical mode shows a frequency of 65 MHz and a mechanical quality factor of 376. The optical spring effect, optical damping, and amplification are observed with a large experimental optomechanical coupling rate g(om)/2 pi of 154 GHz/nm, corresponding to a vacuum optomechanical coupling rate g*/2 pi of 707 kHz. With sub-mW or less input power levels, the cavity exhibits strong parametric oscillations. The phase noise of the photonic crystal optomechanical oscillator is also measured. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4719107]