Principle of nulling recombination on a single-mode fiber: on the left are the superimposed fringe pattern of a classical interferometer (black) and of a Bracewell interferometer (red). The amplitude of the black line is smaller on purpose, since it is supposed to correspond to the planet amplitude. On the right, a close-up of the central part of the fringes is shown with a shaded area that delineates the core of the single-mode optics which achieves the summation of the electric field it receives. The anti symmetric character of the Bracewell fringes (star signal) leads to the nulling effect, while the symmetry of the planetary electric field preserves the signal.