Analysis of optical interferometric displacement detection in nanoelectromechanical systems

Abstract

Optical interferometry has found recent use in the detection of nanometer scale displacements of nanoelectromechanical systems (NEMS). At the reduced length scale of NEMS, these measurements are strongly affected by the diffraction of light. Here, we present a rigorous numerical model of optical interferometric displacement detection in NEMS. Our model combines finite element methods with Fourier optics to determine the electromagnetic field in the near-field region of the NEMS and to propagate this field to a detector in the far field. The noise analysis based upon this model allows us to elucidate the displacement sensitivity limits of optical interferometry as a function of device dimensions as well as important optical parameters. Our results may provide benefits for the design of next generation, improved optical NEMS. © 2005 American Institute of Physics.