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Proceedings Paper

Bandgap tuning induced by polymer deformation in PSCLCs with positive dielectric anisotropies (Conference Presentation)
Author(s): Vincent P. Tondiglia; Kyung Min Lee; Timothy J. White

Paper Abstract

Recently, we demonstrated large magnitude tuning (1500nm) of reflection band in polymer stabilized cholesteric liquid crystals (PSCLCs) formulated with negative dielectric anisotropy (negative ) liquid crystals with low polymer content (~5% by wt.). Evidence suggests an ionic charge (cation) trapping mechanism by the polymer network which subjects the material system to pitch expansion near the positive electrode and pitch compression near the negative electrode resulting in a nonlinear pitch variation throughout the cell thickness when under the influence of a direct current (DC) field. Thus far this effect has only observed PDLC systems with near zero and negative dielectric anisotropies. In general, the field interaction in systems with negative  stabilize the cholesteric structure as the field strength increases while those systems with positive become are dominated by higher fields becoming homeotropic. Here we explore a PSCLC system with a positive  that suppresses the Fréedericksz transition to homeotropic at low field strengths allowing for a unique combination of switching and tuning of the reflection band. This kind of electro-optical control of the reflection band in PSCLCs may have potential use as optical filters, display technologies, telecommunications and tunable lasers.

Paper Details

Date Published: 2 November 2016
PDF: 1 pages
Proc. SPIE 9940, Liquid Crystals XX, 99400P (2 November 2016); doi: 10.1117/12.2237744
Show Author Affiliations
Vincent P. Tondiglia, Air Force Research Lab. (United States)
Kyung Min Lee, Air Force Research Lab. (United States)
Timothy J. White, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 9940:
Liquid Crystals XX
Iam Choon Khoo, Editor(s)

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