**Abstract**

Integrated optics (IO) microsystems, based on guided wave and photonics structures, can find interesting developments for optical interferometric analysis in sensing applications. In fact, IO interferometric microsystems can act as transducers of the information carried on by an optical signal and originated along the signal optical path. In addition, the application of Integrated Optics and Photonics techniques, allow producing very small size and reduced power consumption instrumentation. These features explain the reason why the IO microsystems for interferometric analytics know an increasing interest in many areas such as Astrophysics, Environment, Biosciences, Space and Earth Exploration, Safety and Security. This chapter starts by synthetically describing the basics of the main analytical techniques covered by IO micro-devices. A discussion of the integrated micro-device fabrication procedures, with an analysis of the implied performance limitations, follows. Finally, a description of new generation optical interferometric microsystems, applied to different scientific and technical areas, completes the chapter.

**Keywords:** optical interferometry, Fourier transform interferometry, integrated optics, photonics, integrated optical sensors, Mach–Zehnder micro-interferometers, MEOS sensing devices
