Kasyanyuk D. Control of phase and light polarization and transport of micro- and nanoparticles by means of liquid crystal structures with topological defects.

Influence of spatially inhomogeneous distribution of liquid crystal (LC) director in polarizing twist-elements on a structure of light field was studied as well as application of LC twist-elements for investigation of LC matrix chirality, topological defects, periodical alignment and manipulation of micro- and nanoparticles. Appearance of a wave front dislocation caused by influence of geometrical phase during adiabatic rotation of a polarization plane of light in Mauguin regime was demonstrated using LC ?-cells. A state of the output polarization becomes spatially modulated in the case of a spatially-dependent angle of the director in a LC twist cell, thus opening a possibility of a phase and light polarization control. In places where LC elastic properties causes a hop of a LC director twist on 180° an orientation (topological) defect, a disclination, appears. Giant cholesteric pitches, reaching a centimeter scale, were experimentally measured first time using a disclination of the ?-cells. Linear dependence of a reciprocal cholesteric pitch on a chiral dopant concentration was demonstrated. Rotation of the disclination line in the ?-cells, linear shift of the disclination lines array in polarization gratings and deformation (curving) in two-dimensional polarization gratings were shown under thermo- and photoinduced variations of the cholesteric pitch. Effective trapping of micro- and nanoparticles by disclinations in a LC bulk was demonstrated and a new method for micro- and nanoparticles assembling and their following manipulation was proposed. Single chains, as well as 1D and 2D arrays of micro- and nanoparticle chains, were produced. A possibility of rotation, translation and deformation of the formed particle chains due to photo-induced variations of the LC chirality was demonstrated. Possibility of electroinduced formation and manipulation of nanoparticle chains was demonstrated.