Dissertations

Ledney M.F.

16.12.2014

Orientational instabilityand ordering of confined liquid crystals in external fields
Doctor of Science in Physics and Mathematics
01.04.02 – Theoretical Physics

The theory of threshold spatially periodic Freedericksz transition in a planar nematic liquid crystal (NLC) cell with a finite homogeneous and spatially periodic anchoring energy in an electric and light field was developed. The threshold orientational instability of director in a homeotropic oriented NLC witha spatially periodic anchoring energy in a light field with a spatially modulated intensity was investigated.The theory oflight induced threshold Freedericksz transition in the field of a light beam withabounded crosssize in a homeotropic oriented nematic cellwith a finite homogeneous anchoring energy which is placed in an external static electric field was developed. The threshold light induced Freedericksz transition in a cylindric metal waveguide filled up with NLC was investigated. The theory of the propagation and interaction of coupled TE-wave modes in planar dielectric and metal waveguides with the NLC layer spatially confined in the direction of propagation, in which a diffraction grating of director had been created, was developed.The theory of light scattering by static NLC director fluctuations with the spherical and cylindrical inclusions was developed.The influence of flexoelectric field, created by the static deformations of director near the surface of macroscopic inclusions, on the correlation of the thermal director fluctuations of NLC with inclusionswas investigated.

Keywords: nematic liquid crystal,Freedericksz transition, anchoring energy, orientational instability, flexopolarization, light scattering, director fluctuations

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