Abstract : Thanks to its very high angular resolution, optical interferometry is a technic perfectly suited for the study of the most inner regions of complex objects like young stars and their close environment, active galactic nuclei or interacting binaries. Quick and reliable image reconstructions are now possible thanks to the new instruments PIONIER at the VLT Interferometer or MIRC at the CHARA array, combining 4 or 6 telescopes. However interferometers strongly suffer from atmospheric turbulence so that they need fringe trackers, instruments which compensate these disturbances, then allowing to increase the sensitivity of interferometers by a factor of 10 to 1000. In the first part of my thesis, I present the result of different studies aiming at defining an optimized fringe tracker for 2nd generation instruments at the VLTI. I first demonstrate the interest of single-mode filtering in the framework of fringe tracking, as well as the fundamental importance of Adaptive Optics systems for interferometry, even on 1- or 2-m class telescopes. Second, I determine the most efficient ways to measure the fringe position and the telescopes combination scheme with the best compromise between sensitivity and robustness when combining 4, 6 or 8 telescopes. These studies finally led to the fringe sensor cnocept POPS proposed to ESO by the IPAG. In the second part of my thesis, I focused on interacting binaries. Their study could bring a wealth of information into several fields because of the diversity of physical processes at play. Observations of these systems at very high angular resolution with optical interferometry is a complementary tool to more classical techniques. I focused on the system SS Leporis that was observed with the instruments AMBER and PIONIER. We obtained the first image reconstructions of an interacting binary at the VLTI. These observations led us to a fundamentally new view of this particular system and pave the way to the study of interacting binaries at the VLTI.