In this paper, electro-optical properties of sandwich-like cells utilizing polymers (either weakly conducting or ferroelectric) and nematic liquid crystals are reported. The tuning of the threshold voltage for electrically controlled birefringence is demonstrated. Physical mechanisms of this tuning are discussed.
We suggest to use photoinduced photogalvanic electrical discharges produced by the ferroelectric Fe: LiNbO3 crystals for effective water splitting for production of oxygen and hydrogen by pulsed electrolysis. Electrical self-pulsations may be initiated by CW illumination with incoherent light, including Sun-light. Electrical pulses ( in microsecond range and with kV amplitude) are generated by the bulk photovoltaic (also called photogalvanic) effect. For separation of oxygen and hydrogen gases we apply magnetic field in Hall-effect configuration, with crossed electric and magnetic fields . Adding H-field to the traditional electrolysis scheme in the Hall effect geometry may give new opportunity for control of oxygen and hydrogen production. In this geometry water will be rotated that helps separation of oxygen and hydrogen. Rotation of water explained by the action of Lorentz force in geometry with cylindrical electrodes (cylindrical electrolyzer) that move oxygen and hydrogen bubbles with different signs of charges in the same directions. Hydrodynamic modeling suggest that converse effect: generation of electrical current, when water is rotating in the magnetic field, is possible to realize.
Mesomorphic metal alkanoates is very promising yet overlooked class of nonlinear-optical materials. Metal alkanoates can exhibit a broad variety of condensed states of matter including solid crystals, plastic crystals, lyotropic and thermotropic ionic liquid crystals, liquids, mesomorphic glasses, and Langmuir–Blodgett films. Glass-forming properties of metal alkanoates combined with their use as nano-reactors and anisotropic host open up simple and efficient way to design various photonic nanomaterials. Despite very interesting physics, the experimental data on optical and nonlinearoptical properties of such materials are scarce. The goal of the present paper is to fill the gap by discussing recent advances in the field of photonic materials made of metal alkanoates, organic dyes, and nanoparticles. Optical and nonlinear-optical properties of the following materials are reviewed: (i) mesomorphic glass doped with organic dyes; (ii) smectic glass composed of cobalt alkanoates; (iii) semiconductor nanoparticles embedded in a glassy host; (iv) metal nanoparticles - glass (the cobalt octanoate) nanocomposites.
There are two switching processes where observe in polymer-dispersed liquid crystals (PDLC) when pulse electric field applied: - Slow switching process with rise time hundreds microseconds; - Fast switching process with nanoseconds rise time. The result of research, design and testing ultra-fast PDLC optical gate is presented. The feasibility of 100 nsec rise time optical gate with 1 square inch crystal clear transmission (better than 1.54 dB) and attenuation in OFF state more than 26 dB (30.4 dB for two serial layers) for non-polarized light has been shown.