Self-formation of multiple spatial photovoltaic solitons

We have observed self-formation of one-dimensional multiple dark-grey photovoltaic solitons in iron-doped LiNbO3 samples. The solitons arise from a single initial dark stripe induced by a phase jump in a uniform beam. An odd number of solitons is generated, which depends on the initial stripe width. The dynamics of the soliton formation reveals that the multiple solitons appear in a quasi-steady state regime. Our experimental observations are modelled successfully with a time-dependent nonlinear numerical beam propagation method.