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Proceedings Paper

Laser trapping of low refractive index colloidal particles in a nematic liquid crystal
Author(s): Igor Muševič; Miha Škarabot; Miha Ravnik; Igor Poberaj; Dušan Babič; Natan Osterman; Andriy Nych; Ulyana Ognysta; Vassili Nazarenko; Slobodan Žumer
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Paper Abstract

We describe and analyze laser trapping of small colloidal particles in a nematic liquid crystal, where the index of refraction of colloidal particles is smaller compared to the indices of the liquid crystal. Two mechanisms are identified that are responsible for this anomalous trapping: (i) below the optical Freedericksz transition, the trapping is due to the anisotropic dielectric interaction of the polarized light with the inhomogeneous director field around the colloidal particle, (ii) above the optical Freedericksz transition, the optical trapping is accompanied by the elasticity-mediated interaction between the optically distorted region of a liquid crystal and the particle. In majority of the experiments, the trapping above the Freedericksz transition is highly anisotropic. Qualitative agreement is found with a numerical analysis, considering nematic director elastic distortion, dielectric director-light field coupling and optical repulsion due to low refraction index colloid in a high index surroundings.

Paper Details

Date Published: 15 September 2006
PDF: 9 pages
Proc. SPIE 6332, Liquid Crystals X, 63320V (15 September 2006); doi: 10.1117/12.680971
Show Author Affiliations
Igor Muševič, J.Stefan Institute (Slovenia)
Univ. of Ljubljana (Slovenia)
Miha Škarabot, J.Stefan Institute (Slovenia)
Miha Ravnik, Univ. of Ljubljana (Slovenia)
Igor Poberaj, Univ. of Ljubljana (Slovenia)
Dušan Babič, Univ. of Ljubljana (Slovenia)
Natan Osterman, Univ. of Ljubljana (Slovenia)
Andriy Nych, Institute of Physics (Ukraine)
Ulyana Ognysta, Institute of Physics (Ukraine)
Vassili Nazarenko, Institute of Physics (Ukraine)
Slobodan Žumer, J. Stefan Institute (Slovenia)
Univ. of Ljubljana (Slovenia)

Published in SPIE Proceedings Vol. 6332:
Liquid Crystals X
Iam-Choon Khoo, Editor(s)

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