Liquid crystal textures and optical characterization of a dye-doped nematic for generating vector beams

Abstract

In the present work, liquid-crystal (LC) textures with non-uniform directorfield configurations and azimuthal singularities are considered from the viewpoint of their applications for generating vector and scalar optical vortex beams. To generate a composite vector beam, a LC sample should be light-absorbing and dichroic. For generating a scalar vortex beam, a fork-like defect should be formed in a LC cell. To assess quantitatively these possibilities, we perform optical characterization of a dyedoped nematic. Namely, we employ known characterization techniques for measuring ordinary and extraordinary light absorption indices, linear dichroism, dispersion of linear-birefringence increment, and a scalar orientational order parameter. Since a light-absorbing dopant used by us is a fluorescent dye, the vector beams can be obtained in either transmitted or fluorescent lights. For this reason, we also measure the fluorescence of our dye-doped nematic.