Optomechanics in an ultrahigh-Q two-dimensional photonic crystal cavity

We demonstrate an ultrahigh-Q slotted two-dimensional photonic crystal cavity capable of obtaining strong interaction between the internal light field and the mechanical motion of the slotted structure. The measured optical quality factor is Q=1.2×106 for a cavity with an effective modal volume of Veff=0.04(λ)3. Optical transduction of the thermal motion of the fundamental in-plane mechanical resonance of the structure (νm=151 MHz) is performed, from which a zero-point motion optomechanical coupling rate of g∗/2π=320 kHz is inferred. Dynamical back-action of the optical field on the mechanical motion, resulting in cooling and amplication of the mechanical motion, is also demonstrated.