Cavity optomechanics with photonic crystal nanomembrane

The authors have developed small radius of curvature coupling mirrors integrated in a 100 μm length cavity. The detection sensitivity of this system is at the 10^-16 m/(Hz)^1/2 level allowing us to observe its thermal noise. This sensitivity is also theoretically sufficient to observe ground state quantum fluctuations of the photonic crystal nanomembrane. As any active cooling relies on adding a viscous damping force and has the reduction of the Q-factor of the resonator as a consequence. It is then crucial to design a device with a very high mechanical quality. Different geometries, materials, and stresses for the membrane have been tested. The authors have achieved to realize structures with a Q-factor of 20 000 at room temperature and 65 000 at 20 K.