Sign reversal of the linear electro-optic effect in the chiral nematic phase

The chiral nematic phase aligned with its helical axis along one preferred direction, being parallel to the confining substrates, exhibits a linear electro-optic effect when an electric field is applied normally to the substrates. The effect is considered to be of flexoelectric origin. A sign reversal of the effect is found when the helix of the chiral nematic phase changes its handedness, thus revealing the relationship between the sign of the linear electro-optic effect and the helix handedness. Here, we present and discuss a simple model of this relationship.