Paper
15 June 2001 Novel highly efficient hybrid photoconducting polymer-liquid crystal structures and their application for optical beam processing
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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.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stanislaw Bartkiewicz, Andrzej Miniewicz, and Francois Kajzar "Novel highly efficient hybrid photoconducting polymer-liquid crystal structures and their application for optical beam processing", Proc. SPIE 4279, Organic Photonic Materials and Devices III, (15 June 2001); https://doi.org/10.1117/12.429366
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KEYWORDS
Liquid crystals

Polymers

Diffraction

Diffraction gratings

Spatial light modulators

Refractive index

Photoresistors

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