GHz optomechanical resonators with high mechanical Q factor in air
  We demonstrate wheel-shaped silicon optomechanical resonators for resonant operation in ambient air. The high finesse of optical whispering gallery modes (loaded optical Q factor above 500,000) allows for efficient transduction of the wheel resonator's mechanical radial contour modes of frequency up to 1.35 GHz with high mechanical Q factor around 4,000 in air. 
Xiankai Sun, King Y. Fong, Chi Xiong, Wolfram H. P. Pernice, and Hong   X. Tang
physics.optics