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Proceedings Paper

Anomalous gradient force on colloidal particles suspended in an optically anisotropic liquid crystal
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Paper Abstract

We report on an observation of attractive gradient force on dielectric particles suspended in a medium with a higher refractive index. This unexpected phenomenon was observed with micron sized silica spheres (n=1.37) suspended in optically anisotropic nematic liquid crystal (no=1.5 and ne=1.7). The newly discovered interaction has a range an order of magnituded bigger than the laser beam waist diameter. Above transition temperature, where nematic order of a liquid crystal is lost, the gradient force becomes repulsive and it's range is reduced to expected values. We attribute an anomalous gradient force in nematic phase to two phenomena: particle dressing with a liquid crystal molecules resulting in a colloid with a higher effective index of refraction than surroundings and laser field induced distortino of nematically ordered liquid crystal molecules.

Paper Details

Date Published: 18 October 2004
PDF: 8 pages
Proc. SPIE 5514, Optical Trapping and Optical Micromanipulation, (18 October 2004); doi: 10.1117/12.559563
Show Author Affiliations
Igor Poberaj, Univ. of Ljubljan (Slovenia)
Miha Skarabot, Jozef Stefan Institute (Slovenia)
Dusan Babic, Univ. of Ljubljan (Slovenia)
Igor Musevic, Univ. of Ljubljan (Slovenia)
Jozef Stefan Institute (Slovenia)

Published in SPIE Proceedings Vol. 5514:
Optical Trapping and Optical Micromanipulation
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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