Stacked integrated double-disks for cavity optomechanics

The coupling of mechanical oscillators and optical cavity modes through scattering forces has received considerable attention in recent years [1]. This interaction provides a way, through the principle of dynamic back action [2], to amplify [2,3] and cool mechanical motion [4–6]. It could also soon provide a practical means to entangle macroscopic mechanical motion with a variety of other quantum systems, including light [7,8]. To date, experimental work has relied upon the optical scattering force to create conditions necessary for observation of dynamical back action effects. However, alongside the scattering force there are also dipole optical forces that can furnish optomechanical coupling. These forces, also referred to as dispersive or gradient forces, have been used to control coupling of a waveguide to a resonator [9] and to couple pairs of waveguides [10,11]. In the present work, a stacked, double-disk whispering gallery system is demonstrated as a new means to cavity optomechanical phenomena. Dipole-force coupling between the disks creates optomechnical coupling, causing displacement of the disks and tuning of the underlying whispering gallery resonances. In comparison to scattering-force-based systems, this double-disk configuration has the significant advantage of providing a larger optomechanical coupling constant, independent of the cavity round trip length.