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Proceedings Paper

Electrooptics of chiral nematics formed by molecular dimers
Author(s): Jie Xiang; Sergij V. Shiyanovskii; Yannian Li; Corrie T. Imrie; Quan Li; Oleg D. Lavrentovich
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Paper Abstract

Electrically induced reorientation of liquid crystal (LC) director caused by dielectric anisotropy is a fundamental phenomenon widely used in modern technologies. We demonstrate an electrooptic effect in a chiral nematic LC with a distinct oblique-helicoidal director deformation. The effect, predicted theoretically in late 1960-ies, is observed in a chiral nematic (cholesteric) in which the ground field-free state of the director is a right-angle helicoid. In the electric field, the director forms an oblique helicoid with the pitch and cone angle controlled by the field. The effect is observed in a dimer nematic material in which the bend elastic constant is much smaller than its twist counterpart. The heliconical structure can be used in two different geometries of a sandwich-type cell, with the axis of the oblique helicoid being either parallel or perpendicular to the bounding plates. In the first case, the structure can be used as tunable diffraction grating controlled by the in-plane electric field. In the second case, the structure represents an optical Bragg reflector in which the wavelength of reflected light is controlled in a broad spectral range (from ultraviolet to infrared and beyond, depending on the composition) by a top-down electric field; it can find applications in reflective displays, tunable color filters and lasers.

Paper Details

Date Published: 7 October 2014
PDF: 9 pages
Proc. SPIE 9182, Liquid Crystals XVIII, 91820P (7 October 2014); doi: 10.1117/12.2062737
Show Author Affiliations
Jie Xiang, Kent State Univ. (United States)
Sergij V. Shiyanovskii, Kent State Univ. (United States)
Yannian Li, Kent State Univ. (United States)
Corrie T. Imrie, Univ. of Aberdeen (United Kingdom)
Quan Li, Kent State Univ. (United States)
Oleg D. Lavrentovich, Kent State Univ. (United States)

Published in SPIE Proceedings Vol. 9182:
Liquid Crystals XVIII
Iam Choon Khoo, Editor(s)

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