Two-membrane Cavity Optomechanics: Non-linear Dynamics and Measurement of the Optomechanical Coupling

Multimode optomechanical systems are attracting an increasing interest for the study of collective dynamical effects. The radiation pressure interaction is inherently non-linear and the effects of such non-linearity on the mechanical motion are easily manifested when the optical cavity is driven on the blue sideband, and optical backaction is responsible for mechanical antidamping. When the latter overcomes the internal mechanical friction, a Hopf bifurcation towards a regime of self-induced mechanical oscillations takes place, with a fixed amplitude, and a free running oscillation phase, which may lock to external forces or to other optomechanical oscillators. This mutual phase-locking of self-oscillating resonators is at the basis of optomechanical synchronization.