Monolithic integration of a nanomechanical resonator to an optical microdisk cavity

Onur Basarir,Suraj Bramhavar,Kamil L Ekinci

doi:10.1364/oe.20.004272

Abstract

We report a Silicon nano-opto-mechanical device in which a nanomechanical doubly-clamped beam resonator is integrated to an optical microdisk cavity. Small flexural oscillations of the beam cause intensity modulations in the circulating optical field in the nearby microdisk cavity. By monitoring the corresponding fluctuations in the cavity transmission via a fiber-taper, one can detect these oscillations with a displacement sensitivity approaching 10 fm·Hz-1/2 at an input power level of 50 μW. Both the in-plane and out-of-plane fundamental flexural resonances of the beam can be read out by this approach - the latter being detectable due to broken planar symmetry in the system. Access to multiple mechanical modes of the same resonator may be useful in some applications and may enable interesting fundamental studies.

Highlights

A nanomechanical resonator [1, 2] stores energy in its mechanical oscillations
We report a Silicon nano-opto-mechanical device in which a nanomechanical doubly-clamped beam resonator is integrated to an optical microdisk cavity
Impressive displacement sensitivities wellbelow 100 fm · Hz−1/2 have been reported on microelectromechanical systems (MEMS) devices [8,9,10,11,12]

Summary

Introduction

A nanomechanical resonator [1, 2] stores energy in its mechanical oscillations. Small perturbations to the resonator typically result in large changes in the amplitude or frequency of these oscillations. Using a typical path-stabilized Michelson interferometer [4,5,6], for instance, one can obtain a displacement sensitivity of ∼ 100 fm · Hz−1/2 at 100-μW-level optical powers This sensitivity is degraded as the device size approaches or becomes smaller than the diffraction limited optical probe spot [7]. In which a nanomechanical resonator is coupled to photonic crystal [21], microdisk [22,23,24], microtoroid [25] and microring [26] cavities, have successfully been demonstrated In this manuscript, we report the design, fabrication and operation of a novel nano-optomechanical device, in which a nanomechanical doubly-clamped beam resonator is integrated to an optical microdisk cavity.

Device design and fabrication

Experimental set up

Measurements

Discussion and conclusions