Waveguiding properties of dark spatial soliton arrays in BTO photorefractive crystal

The objective of this work is to study, numerically and experimentally, the waveguide properties of dark spatial soliton arrays generated in photorefractive media. Experimentally we produced the dark solitons using a He-Ne laser beam and a photorefractive BTO crystal under external electric field to excite the drift nonlinearly. The beam to be guided was obtained from a semiconductor laser at a wavelength where the photorefractive effect was lower. This probe beam was focused in different regions and at different angles with respect to the array. The results obtained shown that the guiding ability of the array depends on the period, the external field and the probe beam angle. Numerical simulations solving the nonlinear Schroedinger equation are in correspondence with the experimental observations.