X-shape Two-Dimensional Photovoltaic Dark Spatial Solitons with Fully Incoherent White Light

We report on the first successful experimental observation of X-shape two-dimensional photovoltaic dark spatial solitons in an anisotropic LiNbO3: Fe crystal with fully incoherent white light beams under odd or even initial conditions. This kind of solitons results from the photovoltaic self-defocusing nonlinearity, which depends on the orientation of the principal axes of the crystal.