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

The dependence of the electrooptical response (the current-voltage characte ristic and the switching time! on the thickness of the cell and on the conc entration of a cholesteric admixture to the nematic liquid crystal is inves tigated in twist cells with twists of 90 degrees and 270 degrees. The condi tions under which the slope of the voltage-contrast characteristics stays t he same or decreases are found. It is observed that the relaxation time of the electrooptic response of a liquid-crystal material decreases significan tly at the boundary of the zeroth and first Grandjean zones. (C) 2000 The O ptical Society of America. [S1070-9762(00)00306-7].