title: Determination of the vacuum optomechanical coupling rate using frequency noise calibration.
abstract: The strength of optomechanical interactions in a cavity optomechanical system can be quantified by a vacuum coupling rate g0 analogous to cavity quantum electrodynamics. This single figure of merit removes the ambiguity in the frequently quoted coupling parameter defining the frequency shift for a given mechanical displacement, and the effective mass of the mechanical mode. Here we demonstrate and verify a straightforward experimental technique to derive the vacuum optomechanical coupling rate. It only requires applying a known frequency modulation of the employed electromagnetic probe field and knowledge of the mechanical oscillator's occupation. The method is experimentally verified for a micromechanical mode in a toroidal whispering-gallery-resonator and a nanomechanical oscillator coupled to a toroidal cavity via its near field.
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, EPFL, 1015 Lausanne, Switzerland.
authors.forename: M L
authors.initials: ML
authors.lastname: Gorodetsky
authors.forename: A
authors.initials: A
authors.lastname: Schliesser
authors.forename: G
authors.initials: G
authors.lastname: Anetsberger
authors.forename: S
authors.initials: S
authors.lastname: Deleglise
authors.forename: T J
authors.initials: TJ
authors.lastname: Kippenberg