Three-dimensional (3D) vector holograms have been formed in twisted-nematic (TN) azo-dye-doped polymer liquid crystal (LC) composites whose director is gradually rotated around the thickness direction in the initial state. Polarization states of diffracted beams were rotated in accordance with the twist angle, and the diffraction efficiency depended markedly on the incident angle. We confirmed that the 3D director distributions corresponded to the polarization modulation caused not only by light interference and the propagation in the LCs but also by the initial orientation of the LCs. In order to explain the observed properties a theoretical model of the periodic reorientation distribution in TN LCs was presented. The Jones matrix method is used to describe the interference of two polarized light beams in the anisotropic media. Then the finite-difference time-domain method was applied to analyze the diffraction properties of the 3D vector holograms recorded in the model medium. (C) 2016 Optical Society of America
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