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Proceedings Paper

Ultrafast switching liquid crystals for next-generation transmissive and reflective displays
Author(s): H. J. Coles; S. M. Morris; S. S. Choi; F. Castles
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Paper Abstract

We describe wide temperature range bimesogenic chiral nematic liquid crystals with high flexoelectro-optic coefficients (e/K),of the order of 2.0 CN-1 m-1, high switching angles, > 160° and 50-100μs response times, which may be used to give gray scale devices in both the ULH texture, with an optimum optical in plane switch of 45° at fields of 2Vμm-1 depending on helix pitch and suitable for LCoS devices, and in the USH or Grandjean texture with a unique optically isotropic "field off" black state and contrast ratios of > 5000:1, using "in plane" electric fields, with switching times of the order of 200μs. The new materials and devices give μs level to level switching and the real potential for colour filter free frame sequential colour switching. Highly reflective Blue Phase devices, stable over a 90°C temperature range, in which an electric field is used to switch the reflection from red to green, for example, will be described. Full RGB reflections may be obtained with switching times of a few milliseconds. New surface and volume activated reflecting N* Grandjean texture devices will also be described. Visible wavelength shifts of ~100nm are reported. These are activated by so called "command" surfaces or nanoscopic ferroelectric inclusions and conventional transverse electric fields. Finally we will briefly mention potential applications including high efficiency RGB liquid crystal laser sources.

Paper Details

Date Published: 18 February 2010
PDF: 10 pages
Proc. SPIE 7618, Emerging Liquid Crystal Technologies V, 761814 (18 February 2010); doi: 10.1117/12.848947
Show Author Affiliations
H. J. Coles, Univ. of Cambridge (United Kingdom)
S. M. Morris, Univ. of Cambridge (United Kingdom)
S. S. Choi, Univ. of Cambridge (United Kingdom)
F. Castles, Univ. of Cambridge (United Kingdom)

Published in SPIE Proceedings Vol. 7618:
Emerging Liquid Crystal Technologies V
Liang-Chy Chien, Editor(s)

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