INP-BASED MICROMACHINED MACH-ZEHNDER INTERFEROMETER STRESS SENSORS

In the field of III-V-based compounds, new functionalities can be reac hed by integrating micromechanical structures with electro-optical fun ctions, in order to fabricate Micro Opto Electro Mechanical Systems (M OEMS). A possible application is an InP-based integrated optical stres s sensor. Such a system is based on a partly suspended waveguide that can be strained under the effect of an external stress. The photoelast ic effect induces a phase shift that can be converted into an intensit y shift of the signal if the device is configurated as a Mach-Zehnder interferometer. This system can be integrated monolithically with the optical source and the photodetector. The mechanical, photoelastic and optical properties of this structure has been simulated in order to c onfigurate the alloy composition of the epitaxial layers and the geome try of the device. Micromachining processes have been developed in ord er to realize InP-based suspended microstructures by sacrificial layer etching and bulk micromachining. Preliminary results showed that the optical behaviour of the waveguides is close to the theoretical analys is. Characterisation of the complete interferometer is underway in our group.