Spatial solitons in liquid crystals

Reorientational phenomenon in liquid crystals is unique for nonlinear optics applications. Recently there have been shown that the reorientational nonlinearity in nematic liquid crystals can govern spatial solitons in both waveguide and bulk geometry. Such solitons require a few milliwats of light power and they can be controlled by the state of light polarisation or an external electric field. In this paper, the theoretical analysis and experimental results on optical solitons in nematic liquid crystals due to the reorientational nonlinearity are reviewed. The discussion of their properties is preceded by a brief introduction to nonlinear optics of liquid crystals.