Dispersion effects on the phase closure term: tests on a fiber interferometer

The phase closure is well known to remove the phase biases in a three-arm interferometer. This property is very useful to avoid the phase effect of the atmosphere in stellar interferometry. In this paper we theoretically investigate the effect of differential dispersion in a three-arm interferometer. We demonstrate that phase closure is corrupted by this spectral behavior. This theoretical analysis is illustrated by experimental results on a fiber version of a stellar interferometer. The good accordance between the numerical simulations and the experimental results valid this model.