Abstract

Spatial solitons due to a reorientational nonlinearity can be 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; [1-2] b) the threshold intensity for the Fréedericks effect is low enough; c) thermal effects do not dominate,[3-4] 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 Fréedericks 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;[1] C) employing low enough powers to prevent local heating and veryfing the polarization dependence.

© 2000 IEEE