Optical self-confinement and waveguiding in planar nematic liquid crystals

Summary form only given. Spatial solitons due to a reorientational nonlinearity can he originated in nematic liquid crystals provided that: (a) the molecular directors are aligned but can be reoriented by a properly polarized optical field and provide an index increase; (b) the threshold intensity for the Freedericks effect is low enough; (c) and that thermal effects do not dominate. The conditions above can be met in a nematic liquid crystal cell by (A) adopting a planar geometry, with molecular directors aligned along the propagation direction of the optical beam; (B) eliminating the Freedericks threshold by applying an external electric field parallel to the optical field polarization, in order to introduce a controlled amount of initial tilt onto the directors; and (C) employing low enough powers to prevent local heating and verifying the polarization dependence.