Soliton-like structures in BTO

We present experimental investigations on photorefractive spatial solitons in thin and long (fiber-like) BTO-crystals (sillenite type). The temporal evolution of the beam width is investigated in dependence of the externally applied dc field and the optical power of the soliton beam. Self-focusing occurs for entrance beam diameters of about 10 μm and an optical power of the HeNe-laser illumination in the range of 50 nW. We observed a reduction of the output beam width of nearly 70% in the steady state. This steady state is reached faster for higher field strengths and intensities. The times needed for soliton formation are restricted by saturation.