Electrooptics of chiral nematics formed by molecular dimers

Jie Xiang*, Sergij V. Shiyanovskii, Yannian Li, Corrie T. Imrie, Quan Li, Oleg D. Lavrentovich

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Citations (Scopus)

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.

Original languageEnglish
Title of host publicationLIQUID CRYSTALS XVIII
EditorsIC Khoo
PublisherSPIE - INT SOC OPTICAL ENGINEERING
Number of pages9
Volume9182
DOIs
Publication statusPublished - 7 Oct 2014
EventConference on Liquid Crystals XVIII - San Diego, California, United States
Duration: 17 Aug 201420 Aug 2014

Publication series

NameProceedings of SPIE
PublisherSPIE-INT SOC OPTICAL ENGINEERING
Volume9182
ISSN (Print)0277-786X

Conference

ConferenceConference on Liquid Crystals XVIII
CountryUnited States
CityCalifornia
Period17/08/1420/08/14

Keywords

  • liquid crystal
  • oblique helicoid
  • chiral nematic
  • electrooptics
  • liquid-crystals
  • field

Cite this

Xiang, J., Shiyanovskii, S. V., Li, Y., Imrie, C. T., Li, Q., & Lavrentovich, O. D. (2014). Electrooptics of chiral nematics formed by molecular dimers. In IC. Khoo (Ed.), LIQUID CRYSTALS XVIII (Vol. 9182). (Proceedings of SPIE; Vol. 9182). SPIE - INT SOC OPTICAL ENGINEERING. https://doi.org/10.1117/12.2062737

Electrooptics of chiral nematics formed by molecular dimers. / Xiang, Jie; Shiyanovskii, Sergij V.; Li, Yannian; Imrie, Corrie T.; Li, Quan; Lavrentovich, Oleg D.

LIQUID CRYSTALS XVIII. ed. / IC Khoo. Vol. 9182 SPIE - INT SOC OPTICAL ENGINEERING, 2014. (Proceedings of SPIE; Vol. 9182).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Xiang, J, Shiyanovskii, SV, Li, Y, Imrie, CT, Li, Q & Lavrentovich, OD 2014, Electrooptics of chiral nematics formed by molecular dimers. in IC Khoo (ed.), LIQUID CRYSTALS XVIII. vol. 9182, Proceedings of SPIE, vol. 9182, SPIE - INT SOC OPTICAL ENGINEERING, Conference on Liquid Crystals XVIII, California, United States, 17/08/14. https://doi.org/10.1117/12.2062737
Xiang J, Shiyanovskii SV, Li Y, Imrie CT, Li Q, Lavrentovich OD. Electrooptics of chiral nematics formed by molecular dimers. In Khoo IC, editor, LIQUID CRYSTALS XVIII. Vol. 9182. SPIE - INT SOC OPTICAL ENGINEERING. 2014. (Proceedings of SPIE). https://doi.org/10.1117/12.2062737
Xiang, Jie ; Shiyanovskii, Sergij V. ; Li, Yannian ; Imrie, Corrie T. ; Li, Quan ; Lavrentovich, Oleg D. / Electrooptics of chiral nematics formed by molecular dimers. LIQUID CRYSTALS XVIII. editor / IC Khoo. Vol. 9182 SPIE - INT SOC OPTICAL ENGINEERING, 2014. (Proceedings of SPIE).
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AB - 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.

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