The influence of chiral strength on the spontaneous polarization and the second-order nonlinear optical susceptibility in ferroelectric liquid crystals

• Published in: Ferroelectrics Vol. 213; no. 1; pp. 23 - 33
• Main Authors: Hermann, D. S., Hult, A., Komitov, L., Lagerwall, S. T., Sahlén, F., Trollsås, M.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.05.1998
• ISSN: 0015-0193; 1563-5112
• DOI: 10.1080/00150199808016466

The influence on the spontaneous polarization and the second-order nonlinear optical susceptibility of the mole fraction of the chiral component in binary mixtures of ferroelectric liquid crystals was studied theoretically. The model is based on the different molecular sizes which 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 spontaneous polarization or the NLO-susceptibility and the mole fraction. A comparison is made with spontaneous polarization measurements performed on a series of systematically synthesized chiral and non-chiral liquid crystal structures, which where mixed in different proportions and combinations. The agreement with experiment is very good, and some model parameters are evaluated. The usefulness of the model is discussed.