On-chip cavity optomechanical coupling

Background: On-chip cavity optomechanics, in which strong co-localization of light and mechanical motion is engineered, relies on efficient coupling of light both into and out of the on-chip optical resonator. Here we detail our particular style of tapered and dimpled optical fibers, pioneered by the Painter group at Caltech, which are a versatile and reliable solution to efficient on-chip coupling. A brief overview of tapered, single mode fibers is presented, in which the single mode cutoff diameter is highlighted. Methods: The apparatus used to create a dimpled tapered fiber is described, followed by a comprehensive account of the procedure by which a dimpled tapered fiber is produced and mounted in our system. The custom-built optical access vacuum chambers in which our on-chip optomechanical measurements are performed are then discussed. Finally, the process by which our optomechanical devices are fabricated and the method by which we explore their optical and mechanical properties is explained. Results: Using this method of on-chip optomechanical coupling, angular and displacement noise floors of 4 nrad/[InlineEquation not available: see fulltext.] and 2 fm/[InlineEquation not available: see fulltext.] have been demonstrated, corresponding to torque and force sensitivities of[InlineEquation not available: see fulltext.] and 132 aN/[InlineEquation not available: see fulltext.], respectively. Conclusion: The methods and results of our on-chip optomechanical coupling system are summarized. It is our expectation that this manuscript will enable the novice to develop advanced optomechanical experiments. PACS codes: 07.60.-j; 07.10.Cm; 42.50.Wk. © 2014, Hauer et al.; licensee Springer on behalf of EPJ.