THE INFLUENCE OF CHIRAL STRENGTH ON THE SPONTANEOUS POLARIZATION AND THE 2ND-ORDER NONLINEAR-OPTICAL SUSCEPTIBILITY IN FERROELECTRIC LIQUID-CRYSTALS

The influence on the spontaneous polarization and the second-order non linear optical susceptibility of the mole fraction of the chiral compo nent in binary mixtures of ferroelectric liquid crystals was studied t heoretically. The model is based on the different molecular sizes whic h the molecules occupy in the mixture and on a model of the rotational distribution of the lateral dipole moment and the hyperpolarizability . The model is found to give a nonlinear relationship between the spon taneous polarization or the NLO-susceptibility and the mole fraction. A comparison is made with spontaneous polarization measurements perfor med on a series of systematically synthesized chiral and non-chiral li quid crystal structures, which where mixed in different proportions an d combinations. The agreement with experiment is very good, and some m odel parameters are evaluated. The usefulness of the model is discusse d.