Vibration Sensor Using Planar Integrated Interferometric Circuit On Oxidised Silicon Substrate

We present the first test of a planar integrated optical interferome-trer used as a microdisplacement or vibration sensor. A schematic diagram of this device is shown figure 1. Essentially, it is a Michelson interferometer achieved with our classical planar structure Si/SiO2/Si3N4/SiO2 [1-2] including : . the grating coupler operating in the third order (period = 2μm) ; . the beam splitter, achieved by local etching of the SiO2 over-layer ; . two mirrors also obtained by etching of the silica followed by an aluminium deposition, in order to lower the T.I.R.* angle ; . and two cleaved faces.