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Proceedings Paper

Light-induced anchoring of dye-doped liquid crystal on ITO and polyvinyl-cinnamate aligning surfaces
Author(s): E. Ouskova; Andrey G. Iljin; Yuri A. Reznikov
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Paper Abstract

We studied alignment of dye-doped liquid crystal (LC) on non-photosensitive aligning surfaces after the irradiation with polarized light of the cell with LC being in a nematic phase. The stable planar alignment of LC 5CB doped with a dye Methyl Red (MR) was observed in the irradiated areas. Light sensitivity, direction of easy axis and thermal stability of the light-induced alignment of LC were different for ITO and fluoro-polyvinyl-cinnamate (PVCN-F) aligning surfaces. The characteristics of the alignment also differed from that obtained with the irradiation of the cells with LC being in the isotropic phase. These results point out at a crucial role of both LC orientational ordering and the nature of the aligning surface in the effect the light-induced anchoring. The ordering of dye molecules results in a formation of an anisotropic dark- adsorbed MR layer on the aligning surface after the cell filling. Therefore, the light-induced easy axis is forming on the background of the dark-adsorbed anisotropic layer of dye molecules, and the final anchoring is determined by the cumulative effect of the dark and light-induced anchoring. The difference in the light-induced anchoring on ITO and PVCN-F surfaces is explained by different mechanisms of light-induced anisotropy in adsorbed MR layer. In the case of ITO surface this mechanism is the isomerization of MR molecules, while the MR molecules desorption/adsorption processes provide light-induced anisotropy in the adsorbed on the PVCN-F surface layer.

Paper Details

Date Published: 30 May 2001
PDF: 7 pages
Proc. SPIE 4418, Eighth International Conference on Nonlinear Optics of Liquid and Photorefractive Crystals, 44180B (30 May 2001); doi: 10.1117/12.428295
Show Author Affiliations
E. Ouskova, Institute of Physics (Italy)
Andrey G. Iljin, Institute of Physics (Ukraine)
Yuri A. Reznikov, Institute of Physics (Italy)

Published in SPIE Proceedings Vol. 4418:
Eighth International Conference on Nonlinear Optics of Liquid and Photorefractive Crystals
Gertruda V. Klimusheva; Andrey G. Iljin, Editor(s)

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