Partially polarized light-induced Freedericksz transition in nematic liquid crystals

The combination of two noncoherent copropagating beams enables us to study the roles of the electromagnetic field symmetry and angular momentum in optically induced Freedericksz transition. The particular choice of the interaction geometry allows one to achieve all-optical control of the spatial and dynamic behavior of orientational modes of this transition. The collective molecular precession rate is continuously controlled via the light angular momentum transfer. This control is coupled with the change of twist deformation of molecular orientation. Corresponding theoretical model is proposed and analytical solutions are obtained, providing insight into the multitype deformation behavior of the orientational transition and the possibility of its optical control. Excellent quantitative agreement between experimental and theoretical results is demonstrated. [S1063-651X(98)10110-1].