We experimentally demonstrate operation of a laterally deformable optical nanoelectromechanical system grating transducer. The device is fabricated in amorphous diamond with standard lithographic techniques. For small changes in the spacing of the subwavelength grating elements, lossy propagating resonant modes in the plane of the grating cause a large change in the optical reflection amplitude. An in-plane motion detection sensitivity of 160 fm/square root(Hz) was measured, exceeding that of any other optical microelectromechanical system transducer to our knowledge. Calculations predict that this sensitivity could be improved to better than 40 fm/square root(Hz) in future designs. In addition to having applications in the field of inertial sensors, this device could also be used as an optical modulator.

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We have fabricated micromechanical oscillators from tetrahedrally coordinated amorphous carbon (ta-C) in order to study mechanical dissipation mechanisms in this material. Cantilever oscillators with either in-plane or out-of-plane dominant transverse vibrational modes and free-free beam oscillators with in-plane modes were fabricated with critical dimensions ranging from 75nm to over 1mm. The resonant frequency and quality factor were measured for all oscillators. The resonant frequencies ranged from a few kilohertz to several megahertz, while the quality factor remained nearly constant at approximately 2–4×103. Possible dissipation mechanisms were evaluated for these oscillators, and it was found that the observed dissipation was not limited by mechanical clamping losses, air damping, thermoelastic dissipation, or dissipation due to phonon-mechanical vibration interactions. However, an extrinsic dissipation mechanism in which dissipation is limited by a spectrum of defects in ta-C was found to be consistent with the observed behavior. Assuming that the mechanical relaxation associated with the dissipative defects is thermally activated, we derive a defect distribution that is relatively flat with activation energies ranging from about 0.35 to over 0.55eV.

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We have experimentally demonstrated operation of a laterally deformable optical NEMS grating transducer. The device is fabricated in amorphous diamond on a silicon substrate with standard lithographic techniques. For small changes in the spacing of the grating elements, a large change in the optical reflection amplitude is observed. An in-plane motion detection sensitivity of 160 1hi/'IHz has been measured, which agrees well with theoretical models. This sensitivity compares favorably to that of any other MEMS transducer. Calculations predict that this sensitivity could be improved by up to two orders of magnitude in future designs. As well as having applications to the field of accelerometers and other inertial sensors, this device could also be used as a modulator for optical switching.