(2D+1) spatial optical solitons in dye doped liquid crystals

We report on the observation of (2D + 1) optical spatial solitons in dye do ped liquid crystal. The presence of the dye in the liquid crystal enhances the thermal non-linearity of the medium and yields the orientational one to occur for beam powers in the range of mW. As the power of the input beam i s increased, two specific modes of propagation which are similar to spatial optical solitons are observed. However, it is experimentally observed diff erent behaviors for the low and high power modes: energy profiles, interact ion of two similar modes (collisions). This suggests that the non-linear pr ocesses involved are different for the low and high power soliton modes. Ex perimental results obtained in cylindrical and planar cells are presented t o discriminate the roles of the thermal and orientational non-linearities. In planar cells, a quasi-static field is applied to stiffen the director. I t turns out that the low power mode looks originated by the thermal effect alone. (C) 2001 Elsevier Science B.V. All rights reserved.