Surface-assisted photoalignment in dye-doped liquid-crystal films

C.-R. Lee, T.-L. Fu, K.-T. Cheng, T.-S. Mo, and A. Y.-G. Fuh
Phys. Rev. E 69, 031704 – Published 22 March 2004
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Abstract

This study examines the surface-assisted photoalignment effect of dye-doped liquid-crystal films having a homogeneous alignment. Observations made using a polarizing optical microscope, a scanning electronic microscope, and an atomic force microscope confirm that the morphology of laser-induced surface-adsorbed dyes at the command surface strongly affects the orientation of liquid crystals (LC’s) in a manner that depends significantly on the intensity and duration of the pumping. In weak-intensity regime, a homogeneous and fine layer of adsorbed dyes competes with a layer of ripple structure in reorienting LC’s. These two effects dominantly cause LC’s to reorient perpendicular and parallel to the polarization direction of the pump beam in the early and late stages, respectively. In the high-intensity regime, rough and inhomogeneous ribbonlike adsorbents produced by rapid and random aggregation and adsorption form on the top of the preformed microgrooves, reorienting LC’s irregularly. This surface morphology does not enable photoalignment.

  • Received 8 August 2003

DOI:https://doi.org/10.1103/PhysRevE.69.031704

©2004 American Physical Society

Authors & Affiliations

C.-R. Lee, T.-L. Fu, K.-T. Cheng, and T.-S. Mo

  • Department of Physics, National Cheng Kung University, Tainan, Taiwan 701, Republic of China

A. Y.-G. Fuh*

  • Department of Physics and Institute of Electro-optics, National Cheng Kung University, Tainan, Taiwan 701, Republic of China

  • *Author to whom correspondence should be addressed. Electronic address: andyfuh@mail.ncku.edu.tw

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Vol. 69, Iss. 3 — March 2004

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