Optical Fréedericksz transition in liquid crystals and transfer of the orbital angular momentum of light.

Multistability, out-of-polarization-plane reorientation, and persistent oscillations have been observed in the optical Fréedericks transition in a homeotropically aligned nematic film using a normally incident linearly polarized laser beam with elliptical rather than circular cross section. These features could be ascribed to the presence of an additional optical torque connected with a transfer of the orbital angular momentum of light to the liquid crystal film. A model based on Ritz's variational method confirms this picture.