E. P. Pozhidaev

Light modulation characteristics of a single-polarizer electro-optical cell based on polymer dispersed ferroelectric liquid crystals

Features of the light passing through a single-polarizer electro-optical cell based on a uniaxially oriented film of a polymer dispersed ferroelectric liquid crystal have been studied. The optical response as a function of the applied electric field is shown to depend on the cell geometry. A detailed analysis is presented of the dependence of the maximum light transmission, modulation depth and contrast ratio on the angle between the light polarization and the film orientation direction, on its optical anisotropy and on the molecular tilt angle. An approximate formula is proposed to estimate the highest attainable contrast. Parameters under study have been measured for PDFLC films varying in optical anisotropy value. The experimental results prove to be in good agreement with theoretical estimations.

Modeling electrooptical effects in Ferroelectric Liquid Crystals. 2. V-Shape Switching in the SmC* phase

The thresholdless, hysteresis-free V-shape electrooptical switching in surface stabilized ferroelectric liquid crystal (FLC) cells has been modeled and the results compared with experimental data. High frequency V-shape switching (at f>100 Hz) was experimentally demonstrated and simulated numerically. The key role of the capacitance C of FLC aligning layers has been underlined: thin layers with large C promote the well known bistability effect, thick layers, on the contrary, are necessary for V-shape switching. The results of modeling are in quantitative agreement with experiment.

Comparative analysis of basic physical properties of a ferroelectric liquid crystal and a polymer dispersed ferroelectric liquid crystal

A polymer film of polyvinylbutyral with dispersed droplets of a ferroelectric liquid crystalline mixture (FLC309c) has been prepared and characterized. The collective processes have been studied by dielectric relaxation spectroscopy in the frequency range 10 Hz to 13 MHz. In comparison with the FLC309c mixture, the polymer dispersed ferroelectric liquid crystal (PDFLC309c) based on FLC309c exhibits a Goldstone-like mode relaxation with a much higher relaxation frequency, but a smaller dielectric strength than the Goldstone mode observed for the FLC309c mixture. The spontaneous polarization of PDFLC309c decreases by nearly one order of magnitude in comparison with FLC309c, while the tilt angle decreases by 20%. Considering these results, we believe that a non-switching region exists near the polymer boundaries and that significant deformations of the helical structure occur due to stronger anchoring.

Electrically controlled birefringence of deformed helix ferroelectric liquid crystals

Dependencies of the effective birefringence Δneff:(λ, V) of deformed helix ferroelectric (DHF) liquid crystals on the light wavelength λ and supplied voltage V are investigated.

Light Polarization Modulation with Ferroelectric Liquid Crystals

ABSTRACT This article is devoted to the investigation of light modulating properties of ferroelectric liquid crystals (FLCs). In this work two types of FLC modulators are investigated, namely, the modulator with planar alignment of FLCs operating in high frequency V-shaped mode and the modulator based on deformed helix FLC with homeotropic alignment. It was demonstrated, for the modulator of the first type, that the inversion frequency can be as high as 1 kHz due to the optimized structures of the FLC cell. For the modulators of the second type, we theoretically showed that its performance also strongly depends on geometrical properties of the cells. Both types of modulators can find applications in many fields (e.g. telecom, polarimetry, etc.)

Light modulation characteristics of single-polarizer PDFLC films

Abstract Typical textures of ferroelectric liquid crystal droplets dispersed in a thermoplastic matrix are presented. Uniaxially aligned droplets with wavy deformed smectic layers are effective light scattering polarizers, the direction of which can be reoriented by an applied electric field. We have studied theoretically and experimentally the dependencies of the light modulation characteristics of a single polarizer electrooptical cell based on a planar-oriented film of polymer dispersed ferroelectric liquid crystals both on the geometry of the cell and the material parameters.

FERROELECTRIC LIQUID CRYSTALS FOR NON-DISPLAY APPLICATIONS

A brief review of non-display devises based on ferroelectric liquid crystals (FLCs) is presented. The development of ferroelectric liquid crystal materials and corresponding electrooptical elements for non-display applications have been considered.

Low voltage and high optical quality polymer dispersed FLC films

Abstract Polymer dispersed ferroelectric liquid crystal films were prepared and investigated. The saturation voltage less than 10 V, the polarized light transmittance 628%at the contrast ratio 45:1 or 75%at the contrast ratio 10:1 were reached.

Low Voltage Light Modulator Based on FLC Layer Divided by Polymer Walls

Abstract The structural and electrooptical properties of low-voltage composite material are discussed. The material presents a planar-oriented layer of ferroelectric liquid crystal divided into smaller sections by polymer walls and may be used in light modulators with geometry of crossed polarizers.

Variable optical attenuator based on deformed helix ferroelectric liquid crystals

An optical device for the attenuation (modulation) of the intensity of unpolarized light was developed. Compared to another methods this apparatus allows a low loss ratio of unpolarized light. The switching time and contrast ratio can be 30 /spl mu/s and 300, respectively.