Effect of small cholesteric admixtures on the electrooptical characteristics of nematic liquid crystal cells

The dependence of the electrooptical response (the current-voltage characteristic and the switching time! on the thickness of the cell and on the concentration of a cholesteric admixture to the nematic liquid crystal is investigated in twist cells with twists of 90 degrees and 270 degrees. The conditions under which the slope of the voltage-contrast characteristics stays the same or decreases are found. It is observed that the relaxation time of the electrooptic response of a liquid-crystal material decreases significantly at the boundary of the zeroth and first Grandjean zones. (C) 2000 The Optical Society of America. [S1070-9762(00)00306-7].