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Proceedings Paper

Novel highly efficient hybrid photoconducting polymer-liquid crystal structures and their application for optical beam processing
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Paper Abstract

A novel liquid crystal panel suitable for real-time holography and exhibiting a very high exponential gain coefficient is presented and discussed. It consists of a nematic liquid crystal layer sandwiched between photoconducting polymeric layers. Under exposition to sinusoidal light intensity pattern the panel shows an efficient formation of the refractive index grating. Three different photoconducting polymers were used: poly(3-octyl thiophene), poly(3-octyl thiophene) functionalized with disperse red #1 and polyvinyl carbazole (PVK) doped with TNF. The first order diffraction efficiency, measured in degenerate two wave mixing experiments, depends on the photoconductor used and reaches 44% with PVK:TNF. The panel shows also the ability to switch energy from beam to beam. In the two-wave coupling experiment multiple orders of diffraction are present and a very high two-beam coupling gain is obtained. The largest value of net gain g equals 12 and the corresponding exponential gain coefficient (Gamma) equals 3700 cm-1 were again observed with PVK:TNF. This was achieved in samples biased by a dc external electric field and tilted with respect to the beam incidence bisector at 15 degrees. The time constants of grating formation and its erasing in the studied system depend on the applied voltage and can be made as short as few milliseconds in favorable conditions.

Paper Details

Date Published: 15 June 2001
PDF: 10 pages
Proc. SPIE 4279, Organic Photonic Materials and Devices III, (15 June 2001); doi: 10.1117/12.429366
Show Author Affiliations
Stanislaw Bartkiewicz, Wroclaw Univ. of Technology (Poland)
Andrzej Miniewicz, Wroclaw Univ. of Technology (Poland)
Francois Kajzar, CEA-LETI (France)

Published in SPIE Proceedings Vol. 4279:
Organic Photonic Materials and Devices III
Bernard Kippelen; Donal D. C. Bradley, Editor(s)

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