Two-Dimensional Phononic-Photonic Band Gap Optomechanical Crystal Cavity

We present the fabrication and characterization of an artificial crystal structure formed from a thin film of silicon that has a full phononic band gap for microwave X-band phonons and a two- dimensional pseudoband gap for near-infrared photons. An engineered defect in the crystal structure is used to localize optical and mechanical resonances in the band gap of the planar crystal. Two- tone optical spectroscopy is used to characterize the cavity system, showing a large coupling (g(0)/2 pi approximate to 220 kHz) between the fundamental optical cavity resonance at omega(o)/2 pi = 195 THz and colocalized mechanical resonances at frequency omega(m)/2 pi approximate to 9.3 GHz.