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The characteristics of electric-field-controlled diffraction elements based on a nematic liquid crystal and a new photoalignment polymer have been studied. The photocross-linking of this polymer allows periodic oriented structures and liquid crystal phase gratings with a 30% diffraction efficiency in the first order to be formed.

This paper is devoted to the investigation of the diffraction characteristics of a multilayer optical structure, represented by a two-dimensional phase lattice formed in thin-film layers of nematic polymerizable liquid crystal (PLC). In order to generate periodically ordered liquid-crystal (LC) domains with dimensions of 5–10 µm, which form an anisotropic LC grating, the layer-by-layer patterned photoalignment technology of the water-soluble azo dye AbA-2522 was used. The possibilities of spatial-polarization control of light beams by means of developed one- and two-dimensional diffractive LC structures have been studied experimentally. Our results are promising from the point of view of development and creation of LC-devices for solving current problems of polarization photonics.

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The peculiarities of the linearly polarized light beam reflection at the interface within the bulk of a nematic liquid crystal (NLC) cell with different orientations of the director are analyzed. Two methods to create the interface are considered. Combination of the planar and homeotropic orientations of the NLC director is realized by means of a spatially structured electrode under the applied voltage. In-plane patterned azimuthal alignment of the NLC director is created by the patterned rubbing alignment technique. All possible orthogonal orientations of the LC director are considered; the configurations for realization of total internal reflection are determined. The revealed relationship between the propagation of optical beams in a liquid crystal material and polarization of laser radiation has enabled realization of the spatial separation for the orthogonally polarized light beams at the interface between two regions of NLC with different director orientations (domains). Owing to variations in the applied voltage and, hence, in the refractive index gradient, the light beam propagation directions may be controlled electrically.

Liquid crystal (LC) elements with an electrically controlled spatial topology of director orienta tion have been developed and manufactured. Waveguide light beam propagation mode in a spatially struc tured LC cell has been realized for the first time; the possibility of creating electrically controlled waveguide dividers and adders has been demonstrated experimentally.

The energy and spectral conditions for single-stage holographic recording of a diffraction optical element based on the carbazole-containing azo polymer, that forms singular light beams (optical vortices), have been established. With the atomic-force microscopy (AFM), the surface morphology of the recorded relief holograms was studying, and their diffraction efficiency has been estimated. The topology of the generated optical phase singularities has been studied and the stability range of an optical vortex having the topological charge l = 2 has been found. The possibility of using the developed diffractive optical element in the scheme of optical tweezers for manipulating micro-objects is demonstrated.

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