Order parameter of dual-frequency nematic liquid crystals measured over a wide range of thicknesses

ABSTRACT

Basic physical properties of liquid crystals strongly depend on the orientational order parameter. Given a fundamental importance of this parameter, it was measured for a variety of liquid crystals by means of various experimental techniques. At the same time, the reported results were limited to a relatively narrow range of thicknesses of the studied liquid crystal cells (typically, within a 1–20 µm interval). This paper presents the values of the orientational order parameter of dual-frequency nematic liquid crystals measured over a wide range of thicknesses (from 5 to 200 µm). The non-monotonous dependence of the order parameter S on the cell thickness obtained for relatively thin layers (< 60 µm) of dual-frequency nematics is followed by a rapid monotonous decay of S for thicker (60–200 µm) liquid crystal samples. The obtained results are important for the development of emerging, non-display, applications of liquid crystals utilising thick cells and fast switching materials such as dual-frequency nematics. In particular, they provide a basis for understanding recently discovered two regimes of electro-optical switching of thin and thick layers of dual-frequency nematics (Crystals, 9(6), pp. 314, 2019).

Graphical abstract

KEYWORDS:

• Orientational order parameter
• dual-frequency nematics
• electro-optics
• dichroic dye

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the BioFrontiers Institute, University of Colorado Colorado Springs.