Modeling the colors of phase noise in optomechanical oscillators

Abstract

Optomechanical oscillators (OMOs) combine the co-existing high quality factor mechanical and optical resonances in an integrated device to realize low phase noise RF oscillations. While several attempts to model the phase noise in such oscillators have been reported, the close-to-carrier phase noise models in literature do not account for $1/f^3$1/f3 (pink noise) and higher order slopes in the phase noise spectra. Here we present a phase noise model, corroborated with an experimental characterization of phase noise of two monolithic integrated silicon OMOs, accounting for contributions of thermomechanical and adsorption-desorption (AD) noise to the phase noise. The model shows good agreement with experimental data and provides further insights into the mechanisms underlying the noise processes contributing to different slopes in the phase noise spectra in OMOs.