Direct stabilization of optomechanical oscillators

We demonstrate a simple and effective technique for stabilizing the oscillation amplitude of a radiation pressure driven RF optomechanical oscillator (OMO). By controlling the optomechanical gain through a feedback loop that uses the oscillation amplitude itself as the feedback parameter, we have been able to suppress the amplitude fluctuations and drift. In contrast to more complex techniques that only lock the relative wavelength detuning, the proposed technique isolates the oscillation amplitude not only from laser wavelength variations, but also from laser power variations, ambient temperature variations, and coupling gap variations. The amplitude stabilization also improves the stability of the oscillation frequency (compared to free-running OMOs).