A. L. Andreev

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.

Surface and volume bistability in ferroelectric liquid crystals

We call the bistabifity of ferroelectric liquid crystal (FLC) cells as the surface bistability (SB), if the dispersion part of anchoring energy is responsible for this type of bistabiity. SB was predicted theoretically [1] and investigated experimentally [2-4] .It was shown, that SB there exists in SSFLC cells possessing the bookshelf structure of smectic C layers [2] and SB there exists only in limited region of multidimensional space of cell and driving voltage parameters [3]. Anchoring energy of FLC with solid surface for SB structures is [4]: 102 iO erg / cm2 On the other hand there exists the volume bistability (VB), which have been observed by us recently in thick (15 mkm and more) layers of new FLC compositions [5].VB is a special phenomenon caused only with stereo chemical nature of the FLC composition and quite independent upon surfaces. In this work we would try: to found the physical principle for experimental measurement of an average free energy density of ferroelectrics, -to describe manifestations for both SB and VB, - to compare SB and VB from point of view their free energy parameters.

Gray-scale FLC for SLM and displays

A new principle of continuous gray scale for passively addressed FLC displays and SLM matrices is proposed. It is based on the multistability effect in C*FLC. Conditions of its exhibition are defined. Experimental results for FLC cells and the laser beam intensity attenuator are given.

Advances in FLC electro-optics and FLCD prospects

Advances in the field of studying the electrooptics of ferroelectric liquid crystal and possibilities of their practical use are considered. Liquid crystal compositions are developed with steady bistable and multistable properties and high multiplex ability for composing and displaying blocks of both the binary and analog information in fast spatial light modulators and high resolution information displays. Liquid crystal cells are created with electrooptical response time of a few microseconds.

Advances in ferroelectric liquid crystals for high-speed spatial-light modulators

The developed principles of optimization of the molecular structure and the mixture composition of smectic C* ferroelectric liquid crystal (FLC) are discussed, which significantly allow us to increase the speed of the electro-optic response in planar alignment of FLS. The achieved results reveal opportunity of construction of fast spatial light modulators with multiplexing owing to bistability with the time of electrical addressing about 1 microsecond(s) .

Optimization of light modulation characteristics of polarizer-free PDFLC cells

Modulation characteristics of the light passing through a polarizer-free electrooptical cell based on a double uniaxially oriented film of polymer dispersed ferroelectric liquid crystals (PDFLC) have been studied. Theoretical analysis is presented of the dependence of the maximum light transmission, modulation depth and contrast ratio on the angle between the orientation of PDFLC films, on their optical anisotropy and the molecular tilt angle (Theta) . Parameters under study have been measured, and the experimental results are in good agreement with the theoretical estimations.

Properties of new FLC and prospects of their application in fast optical valves, SLM, and displays

The steady bistable regime in FLC layers was found using FLC compositions with its own (volume) bistability. The grayscale in such a FLC possessing high spontaneous polarization value is demonstrated and explained. The row addressing time 50 mks and multiplexivity 1200 (at optical contrast more than 20:1) are reached in FLC passive addressed matrix. Monostable FLC with 2.5 mks response time (at optical contrast not less than 50:1) can be used in fast optical light valves and active addressed matrices for SLM- spatial filters.