Opto-mechanical accelerometer based on strain sensing by a Bragg grating in a planar waveguide

In this paper we present an opto-mechanical sensor based on a Bragg grating as the strain-sensing element. The motivation for choosing this alternative way of strain sensing is that the sensed information is directly encoded into a wavelength, which is an absolute parameter insensitive to typical intensity and phase noise. Recently, it has been shown that fibre-optic strain sensors based on this technique are capable of resolving dynamic strain down to 0.6 × 10 −9( Hz) −1 2 . To demonstrate that this new detection principle can also be used for high-performance microsensors, we have chosen to fabricate a silicon opto-mechanical accelerometer based on strain sensing by a Bragg grating in a planar waveguide. The fabrication of the accelerometer includes KOH wet etching of (110) silicon, controlling stress in PECVD glass waveguides and direct UV writing of Bragg gratings.