GaAs disks optomechanics

This paper present a study on GaAs optomechanical disk resonators (typically 3 μm diameter and 200 nm thickness) where optical whispering gallery-modes of high quality factor Q (up to 5.10 ) couple to high frequency mechanical modes of the disk, with frequency measured up to 1.5 GHz and masses down to the pg. Optical and mechanical energy are confined in a submicron interaction volume in these structures, leading to an extreme optomechanical coupling for the vacuum coupling. Optical and mechanical modes were modeled not only numerically but also analytically using the system symmetries, that allows to discuss optomechanical selection rules observed in the experiments. Optical and mechanical modes of the resonator are identified in the measurements by their dispersion lines as a function of the disk geometry. The Brownian motion of the disk is resolved with a sensitivity of 10^-17 m/√Hz under ambient conditions, approaching the standard quantum limit imprecision.