The interferometer based on the fiber 3x3 coupler is already a well-known device for measuring displacements and wavelength shifts. TNO is currently working on the fabrication of an integrated version of this versatile interferometer on Silicon-On-Insulator. The integrated interferometer is expected to be far more stable then the fiber version, making it less sensitive to vibrations, temperature and pressure variations. Also the size of the component is much smaller, making it ideal for a variety of new and smaller sensors. This paper describes the current progress on building such an interferometer for measuring small displacement and using it as a Fiber Bragg interrogator.