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| 2. |
- Barbero, G., et al.
(författare)
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Effect of a surface polarized layer on the optical properties of a nematic cell
- 2023
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Ingår i: Journal of Molecular Liquids. - 0167-7322. ; 384
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Tidskriftsartikel (refereegranskat)abstract
- The optical properties of a cell of nematic liquid crystal presenting a tilted surface polarization submitted to an electric field are theoretically investigated. The origin of the surface polarization is assumed to be related to the interaction of the nematic molecules with the substrate and to the polar order due to the cell filling procedure. The analysis shows that the coupling of the surface polarization with the external field has different effects on the two surfaces limiting the sample. On one of them, the coupling gives rise, in an unbounded sample, to a continuous variation of the easy angle, whereas on the other one it is responsible for a first-order like transition of the easy axis orientation. For a sample of finite thickness our analysis shows that in the presence of a coupling between the two surfaces, operated by the elastic properties of the liquid crystal, the abrupt variation of the easy axis on one of the surfaces induces also on the other surface a discontinuity on the nematic surface orientation. The optical transmission of the cell versus the amplitude of the applied voltage, for an impinging monochromatic linearly polarized light, presents a discontinuity for the critical voltage at which the first-order transition of the surface tilt angles appears.
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| 3. |
- Elamain, Omaima Abubakr, et al.
(författare)
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Optically isotropic state in bent core nematic mixtures with rod like molecules induced by direct current electric field
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:16
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Tidskriftsartikel (refereegranskat)abstract
- One of the most important characteristic of the liquid crystal displays is the contrast of the generated images. The dark state of the display is a prerequisite for a high image contrast. Optically isotropic state was observed in bent core nematic mixtures containing rod like molecules induced by low applied dc electric field. It is found that the switching properties of these nematic mixtures depend on the concentration of the rod like molecules. Comparatively high concentrations of rod like molecules in the mixtures resulted in an improvement of the contrast and switching properties of the bent core nematic mixtures, thus demonstrating their potential for display applications.
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| 4. |
- Trollsås, M., et al.
(författare)
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The influence of the molecular structure on the second-order nonlinear optical properties of pyroelectric liquid crystalline polymers
- 1998
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Ingår i: American Chemical Society Symposium Series (ACS). - Washington, DC : American Chemical Society. - 0097-6156 .- 1947-5918. ; 695, s. 315-327
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Tidskriftsartikel (refereegranskat)abstract
- Pyroelectric Liquid Crystal Polymers (PLCP), a novel class of material with intrinsic polar order developed in our laboratory, are discussed. Thin films (2-4µm) of PLCP were prepared by photopolymerization of ferroelectric liquid crystalline monomers in the chiral smectic C (SmC*) phase. The poly(acrylate) materials have been structurally modified in order to improve their nonlinear optical and thermal properties. Further are their longterm nonlinear optical properties discussed based on results from second harmonic generation (SHG), spontaneous polarization (Ps), and dielectric spectroscopy.
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