LATERAL OPTICAL ACCELEROMETER MICROMACHINED IN (100)-SILICON WITH REMOTE READOUT BASED ON COHERENCE MODULATION

A novel type of optical silicon accelerometer is demonstrated. A non-c onventional wet etching technique for (100) silicon allows us to make a highly symmetrical seismic mass with a pure lateral translation move ment. This ensures a low sensitivity to accelerations that are not alo ng the sensing axis, To detect the displacement of the seismic mass du e to accelerations, an optical fiber can be easily and precisely imple mented to form a Fabry-Perot interferometer. A detection method based on coherence modulation allows remote acceleration sensing through a f iber-optic link without any electrical link between the measurement re gion and the signal output. The sensitivity of the demonstrated system is 1.8 V g(-1) for a measurement range of +/- 10g and a resolution of less than 1mg. Moreover, the fabrication technique and the multiplexi ng capability of the detection method open the way to a 3D single-chip accelerometer, the measurements of which could be sent directly throu gh a single optical link. (C) 1998 Elsevier Science S.A. All rights re served.