Interaction Between Two-Dimensional White-Light Photovoltaic Dark Spatial Solitons

Using fully incoherent white light emitted from an incandescent bulb (a line source and amplitude mask, we study experimentally the interaction between two 2D white-light photovoltaic dark spatial solitons with three different separations (40 mu m, 50 mu m and 60 mu m) and arrangement directions (parallel to, perpendicular to and tilted at 4 with respect to the crystalline c axis propagating in parallel in close proximity in self-defocusing LiNbO3:Fe crystal. Experimental results reveal that a 2D white-light dark soliton pair only experiences attractive forces when their mutual separation is sufficiently small (< 60 mu m), and the degree of the attraction depends on their mutual separation and their arrangement direction. When the separation is larger than 60 mu m, the interaction is not evident.