Optical activity and ferroelectricity in liquid crystals.

Some liquid-crystalline phases of optically active materials are themselves optically active and possess dissymmetric structures. The structures of these phases, cholesteric and smectics C*, I*, and F*, possess a helical ordering of their molecules. Plane-polarized light is rotated by the helix, and when its pitch is comparable to the wavelength of visible light, these phases will reflect light of a single color. The smectic phases can exhibit ferroelectricity, and have been utilized recently in fast-switching light-valves. This article is concerned with the microscopic property of molecular configuration and its relationships with optical rotation and ferroelectricity.