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Proceedings Paper

Surface charge screening and boundary conditions for high two-beam coupling gain in pure liquid crystals
Author(s): Andriy Dyadyusha; Malgosia Kaczmarek; Graham Gilchrist; Giampaolo D'Alessandro; Janusz Parka; Roman S. Dabrowski
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Paper Abstract

We report on asymmetric two-beam coupling and the ways of controlling it in liquid crystals cells with photoconducting polymer layers. The cells had one of the substrates covered with a photoconductive polymer layer, namely PVK, photosensitised with C60 to respond to visible light. Efficient gain was measured in 30 micron thick cells with two incident beams having the same intensity. We present a model of two-beam coupling gain based on the build-up and discharge of surface charge screening layers, spatially modulated due to the photoconductivity of doped PVK. The simulation of electric field distribution inside a liquid crystal cell for different two-beam coupling grating spacing showed different penetration of field into the liquid crystal bulk. The characteristics of dynamics, magnitude of two-beam coupling and the efficiency of diffraction were determined for different values of applied DC field, cell configuration and liquid crystals. We found that the direction of energy flow was determined just by the cell tilt and not by the DC field bias.

Paper Details

Date Published: 16 December 2004
PDF: 8 pages
Proc. SPIE 5621, Optical Materials in Defence Systems Technology, (16 December 2004); doi: 10.1117/12.578530
Show Author Affiliations
Andriy Dyadyusha, Univ. of Southampton (United Kingdom)
Malgosia Kaczmarek, Univ. of Southampton (United Kingdom)
Graham Gilchrist, Univ. of Southampton (United Kingdom)
Giampaolo D'Alessandro, Univ. of Southampton (United Kingdom)
Janusz Parka, Military Univ. of Technology (Poland)
Roman S. Dabrowski, Military Univ. of Technology (Poland)

Published in SPIE Proceedings Vol. 5621:
Optical Materials in Defence Systems Technology
Anthony W. Vere; James G. Grote; Francois Kajzar, Editor(s)

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