Mikhailo F. Lednei

Light-Scattering by Small Solid Spherical Particles Dispersed in a Nematic Cell

Abstract The light scattering differential cross-section by small identical spherical particles in nematic liquid crystal is numerically calculated at the infinitely rigid director anchoring with particles surface. It is taking into account the influence of the correlations between the positions of the particles.

Light-Induced Frederiks Transition Threshold in Nematic Cell with an Arbitrary Inhomogeneity of the Director anchoring Energy

Abstract The system of algebraic equations which allow to calculate the light induced Frederiks transition threshold in nematic cell with director inhomogeneous anchoring energy is obtained for a general case of light field with spatially modulated intensity. It is found the analytical expressions for threshold in the case of small deviations of anchoring energy from homogeneous value. At the great ones the results of numerical calculations of threshold for some types of the anchoring energy inhomogeneity are presented. The dependence of threshold on the spatial period of light intensity modulation as well as the anchoring energy parameters is discussed.

Light-Induced Threshold Instability of Nematic Director in Cylindrical Waveguide

Abstract The dependence of director reorientation threshold on the parameters of electromagnetic wave in waveguide as well as director boundary conditions on the waveguide surface is obtained.

Rayleigh-Gans theory of light scattering by liquid crystals filled with cylindrical particles

Light scattering cross-sections by the director inhomogeneity near small cylindrical particles in a nematic cell are calculated in the Rayleigh-Gans approximation. We use the Percus-Yevick approximation to account for interference effects and study the influence of the boundary conditions on the particle surface as well as the effect of an external electric field on the angular dependence and on the magnitude of the light scattering cross-section.

Dynamic holographic gratings in nematic cell with periodic boundary conditions

Abstract Nematic cell with light intensity spatial grating is considered. The influence of periodic spatial modulation of the director anchoring energy and the easy orientation axis at the cell surfaces on the director spatial distribution in the liquid crystal bulk under the action of light is investigated. It is shown that in both cases the director distribution takes the form of a superposition of the cosine gratings with periods which are the linear combinations of the light intensity and boundary condition periods. The Frederiks transition threshold value is calculated for homeotropic cell with periodic modulation of the anchoring energy.

NLC Orientational Instability in the Absorbed Light Wave Field with Spatially Modulated Intensity

Abstract The influence of dipole phototransformed molecules on the orientational instability threshold of homeotropic NLC exposed to spatially modulated light is studied. The orientational spatial distribution of the director is calculated, in linear approximation, at the non threshold director reorientation. It is shown that the orientational instability threshold may significantly decrease (increase) and the optical nonlinearity constant may increase (decrease) by orders of magnitude as phototransformed molecules with typical value of permanent electric dipole appear in the nematics.

Light scattering by small hard particles in liquid crystals in anomalous-diffraction approach

The differential and total light scattering cross sections by LCs which contain hard macroscopic spherical and cylindrical particles are theoretically studied using the anomalous-diffraction approach. The influence of form and size of particles, the type and strength of director anchoring on the particle surface as well as light wave polarization on the light scattering is analysed.

Light-induced Freederiks transition in waveguide with liquid crystal core

Director reorientation threshold in the field of electromagnetic wave in round cylindrical metallic waveguide loaded with nematic liquid crystal is theoretically studied. The dependence of threshold on the frequency and type of electromagnetic wave in waveguide as well as director anchoring energy with waveguide surface is analyzed.

Light Scattering by Large-scale Director Inhomogeneities in Filled Liquid Crystals

This paper presents the results of a theoretical study of light scattering cross-sections in liquid crystals containing small spherical particles, using the anomalous-diffraction approach. We consider the cases of separate particles and particle network in nematics. Particularly it is shown that for a dipole director configuration around the particle the light scattering is about two orders of value stronger than for a Saturn ring one; for a particle network the nature of the network domain orientational distribution influences the intensity of light scattering, but has little effect on its angular dependence.

Computer modeling of light scattering in filled liquid crystals

The differential and total light scattering cross sections by LCs which contain hard macroscopic spherical and cylindrical particles are theoretically studied using the anomalous-diffraction approach. The influence of the form and size of particles, the type and strength of director anchoring on the particle surface as well as light wave polarization on the light scattering is analyzed.