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Proceedings Paper

Optical trapping in liquid crystals
Author(s): F. Simoni; L. Lucchetti; L. Criante; F. Bracalente; F. Aieta
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Paper Abstract

Optical trapping and manipulation of micrometric silica particles dispersed in a nematic liquid crystal is reported. Several kind of samples are considered: homeotropic and planar undoped cells and homeotropic and planar cells doped by a small amount of the azo-dye Methyl-Red. The incident light intensity is over the threshold for optical reorientation of the molecular director. The refractive index of the dispersed particles is lower than the ones of the liquid crystal therefore the usual conditions for laser trapping and manipulation are not fulfilled. Nevertheless optical trapping is possible and is closely related to the optical nonlinearity of the hosting liquid crystal1. Trapping in doped and undoped cells are compared and it is shown that in the first case intensity lower by more than one order of magnitude is required as compared to the one needed in undoped samples. The effect is faster and the structural forces are of longer range. The formation of bubble-gum like defects in doped samples under certain experimental conditions is also reported and discussed.

Paper Details

Date Published: 18 August 2010
PDF: 9 pages
Proc. SPIE 7775, Liquid Crystals XIV, 77750F (18 August 2010); doi: 10.1117/12.860517
Show Author Affiliations
F. Simoni, Univ. Politecnica delle Marche (Italy)
L. Lucchetti, Univ. Politecnica delle Marche (Italy)
L. Criante, Univ. Politecnica delle Marche (Italy)
F. Bracalente, Univ. Politecnica delle Marche (Italy)
F. Aieta, Univ. Politecnica delle Marche (Italy)


Published in SPIE Proceedings Vol. 7775:
Liquid Crystals XIV
Iam Choon Khoo, Editor(s)

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