In order to increase the imaging capabilities and the attainable resolution of the observing instruments in astronomy, the High Angular Resolution prospective proposes to increase the number of sub-apertures of the optical interferometers. Thanks to densification techniques, future interferometers will be capable of imaging faint and small (apparent size) astrophysical targets. The resulting instrumental constraints define the technical and technological challenge in which my Thesis work is performed. The propagation conditions and the recombining quality of the collected beams govern the performances of the image, in terms of stability and instrument sensitivity. To ensure a coherent interferometric mix and the possibility of observing during long integration times, it is necessary to maintain the optical path difference to a value lesser than a fraction of wavelength thanks to a cophasing device. I propose a method dedicated to cophase large interferometers: the Chromatic Phase Diversity. It is based on the spectral analysis of multi-wavelength images allowing to determine in real time the optical path difference to be compensated by the instrument delay lines. After a theoretical and numerical study of the method, I describe its practical implementation on the fibered hypertelescope testbench SIRIUS developed at the Observatoire de la Côte d'Azur (Nice, France).
