LINEAR ELECTROOPTIC EFFECTS IN THE CHIRAL NEMATIC PHASE

A linear electro-optic effect is described in the unwound (infinite or sufficiently long pitch) state of the chiral nematic phase N, and attributed to the electroclinic effect. It is similar to the effect already known in the smectic A phase. In particular, it is characterized by the same speed and its induced tilt is a linear function of the applied field. We have, so far, been able to induce tilts of up to several degrees in this mode. An interpretation of the effect is given, based on the symmetry of the N phase in combination with the aligning property of the surfaces. A similar electro-optic effect of exceptionally large amplitude but slower and much more complex has been found in cylindrical N domains near the clearing point. An induced angle of deflection well over 45 degrees, corresponding to switching angles in excess of 90 degrees can be observed in this case. © 1991 Gordon and Breach Science Publishers S.A.