Effect In Ferroelectric Liquid Crystals Research Articles

Electro-optical effects in ferroelectric liquid crystals

Abstract A brief review is given of main electro-optical effects in ferroelectric liquid crystals (FLC). The characteristics of the effects are compared from the viewpoint of applications. The perspective of electrooptical possibilities of FLC with strongly twisted helical structure is stressed.

Dye guest-host effects in ferroelectric liquid crystals

Abstract Here we present the optic and electro-optic characteristics of ferroelectric dye guest-host devices incorporating different dye and S*C host materials. We demonstrate fast response time (< 100 μs) single polarizer and zero-polarizer device configurations for high order parameter dichroic dyes and single polarizer fluorescent dye devices. The dynamic data include measurements of response times as functions of voltage, temperature and dye concentration, from which we conclude that the inclusion of certain dyes does not adversely affect the ferroelectric phase. The contrast ratios of these novel guest-host devices are also presented and are shown, as expected, to be functions of tilt angle (and therefore temperature). However, we demonstrate that the high tilt angle of 45° is not necessary for high contrast devices, and in fact for certain devices configurations θ = 22½° is optimum. These results are discussed.

Ferroelectric liquid crystal display capable of video line address times

The speed and bistability of the surface-stabilized electro-optic effect in ferroelectric liquid crystals have suggested their application in storage displays free from the multiplexing limitations of fast-scan multiplexed devices. The experimental work reported here demonstrates for the first time that such devices can operate at high levels of multiplexing at video line address times.

Dependence of Switching and Memory Times of Optical Switching Element Utilizing Ferroelectric Liquid Crystals on Thickness of Cell and Material

Switching times rise time, decay time and memory time, of various electro-optic effects in ferroelectric liquid crystals are found to be strongly dependent on the molecular structure, cell thickness and temperatures. Especially in TSM (transient scattering mode) operation, the rise time becomes shorter in liquid crystals with larger spontaneous polarization, at high temperatures and in thinner cell. The decay time is also shorter at higher temperatures, in thinner cells and also in materials with higher relaxation frequency of dielectric constant.

Characteristics of Electro-Optic Effect of Ferroelectric Liquid Crystals in Infrared Range

Optical properties of ferroelectric liquid crystals have been studied in the infrared range. It is revealed that the electrooptic effects in these ferroelectric liquid crystals can be used successfully in the infrared range (∼15µm) for the application in optical communication and sensing etc.

Dynamic Response Of Molecular Orientation In Ferroelectric Liquid Crystals

We present numerical solutions of the equation of motion that governs the dynamics of molecular orientation in ferroelectric liquid crystals (FLCs). The obtained solutions illustrate novel electro-optic effects in FLCs. Specifically, we treat the switching by an applied electrical pulse between two optically distinct stable states, and calculate the requisite pulse width for switching as a function of pulse amplitude. We also show that with appropriate liquid crystal cell preparation, switching between four distinct states is feasible.

Thickness and temperature dependences of dielectric property and electro-optic effect in ferroelectric liquid crystal

Abstract The temperature T m at which the maximum dielectric constant eE m is observed, decreases with decreasing cell thickness. However, in the cell thinner than 10 μm, T m again increases to higher temperatures and E m decreases remarkably. These behaviors can be explained in terms of free energy theory by taking effects of the thickness on the relaxation time into consideration for thicker cells and by taking the hindrance of the molecular motion due to the wall effect into consideration for thinner cells. Characteristics of electro-optic effects of ferroelectric liquid crystals are discussed as a function of the cell thickness and in comparison with the thickness dependence of dielectric properties.