Surface charge screening and boundary conditions for high two-beam coupling gain in pure liquid crystals

Andriy Dyadyusha; Malgosia Kaczmarek; Graham Gilchrist; Giampaolo D'Alessandro; Janusz Parka; Roman S. Dabrowski

doi:10.1117/12.578530

16 December 2004 Surface charge screening and boundary conditions for high two-beam coupling gain in pure liquid crystals

Andriy Dyadyusha, Malgosia Kaczmarek, Graham Gilchrist, Giampaolo D'Alessandro, Janusz Parka, Roman S. Dabrowski

Author Affiliations +

Proceedings Volume 5621, Optical Materials in Defence Systems Technology; (2004) https://doi.org/10.1117/12.578530
Event: European Symposium on Optics and Photonics for Defence and Security, 2004, London, United Kingdom

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.

Citation Download Citation

Andriy Dyadyusha, Malgosia Kaczmarek, Graham Gilchrist, Giampaolo D'Alessandro, Janusz Parka, and Roman S. Dabrowski "Surface charge screening and boundary conditions for high two-beam coupling gain in pure liquid crystals", Proc. SPIE 5621, Optical Materials in Defence Systems Technology, (16 December 2004); https://doi.org/10.1117/12.578530

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