Research on a novel high sensitivity MOEMS deformable nano-grating accelerometer

Abstract

With the development of the military field, there is growing interest in extremely high sensitivity. For meeting this desire, we design a novel high sensitivity MOEMS (Micro-Opto-Electro-Mechanical-System) accelerometer which is based on laterally deformable nano-grating. Calculations predict that this sensitivity could be improved by up to two orders of magnitude in future design and it can reach as high as 10-9g. These sensors consist of two offset layers of sub-wavelength polysilicon nano-gratings. They modulate the near-field intensity and polarization of an incident light source in response to relative motion of the nano-gratings. The reflected/transmitted optical beam intensity from the nano-gratings is measured as a function of the relative lateral positions of the nano-gratings. By using rigorous coupled-wave analysis (RCWA) and Fourier transform methods, we research the theory mechanism about nano-grating accelerometer. The accelerometer belongs to displacement sensors. For small changes in the spacing of the grating elements, a large change in the optical reflection and transmission amplitude observed. An in-plane motion detection sensitivity of 160fm/&radic;<i>HZ</i> has been measured, and its displacement sensitivities will be as low as 12fm/mg. This sensitivity compares favorably to that of any other MEMS (Micro-Electro-Mechanical-System) transducer.