High-quality deformed lying helix in chiral LC on surface with periodic alignment prepared by two-step optical treatment

ABSTRACT

We propose a method for creating a periodic planar-homeotropic alignment (PHA) of liquid crystal (LC) on a film prepared by spin-coating a solution of a mixture of a photosensitive organic azo dye and a surfactant. Irradiation by polarised and non-polarised ultraviolet light provides areas with reliable planar and homeotropic LC alignment, respectively. Using a photomask, gratings with PHA are created, and optical properties of the LC cells based upon them are investigated. For the first time, the characteristic fine features of the field-induced transition of the initially standing chiral LC helix into a Deformed Lying Helix (DLH) configuration with the spiral axis lying in the LC layer plane are visualised and studied. The observed optical images illustrate the high-quality DLH pattern. Numerical simulations of the DLH reveal the peculiarities of the obtained structure and how it is formed.

GRAPHICAL ABSTRACT

KEYWORDS:

• Cholesteric liquid crystal
• planar-homeotropic alignment
• alignment modulation
• deformed lying helix
• numerical simulation

Acknowledgements

The work was supported by the Ministry of Science and Higher Education within the framework of the State Assignment of the Federal Scientific Research Center ‘Crystallography and Photonics’ of the Russian Academy of Sciences.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was supported by the Ministry of Science and Higher Education of Russian Federation.