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Proceedings Paper

Optical manipulation of liquid crystals using a two-beam technique
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Paper Abstract

The development of techniques of optical manipulation of matter attracts great attention. One of the most interesting mechanisms for such manipulation is the dielectric light- matter interaction. This point was used by R. Beth, in 1936, to demonstrate an angular manipulation of a birefringent uniform macroscopic object. We have proposed and developed a two-beam technique that is used for the manipulation of nematic liquid crystal materials. Pertinent external control parameters, such as the mutual polarization of the two beams, the ratio of the two beams' intensity, the total intensity and the interaction geometry, are pointed out. Effective optical control via the non-resonant angular momentum transfer to the cluster of illuminated molecules is predicted and realized experimentally. In particular, it is shown that quasi-uniform precession regimes may be light- controlled at 100 percent. Moreover it is shown that the circularly polarized light-induced breakdown of orientational symmetry in non-chiral liquid crystal may result in their macroscopic chiral organization. Stationary, precessing and oscillating chiral modes are observed which may be controlled via the above mentioned external parameters. Consequently, since the non-planar deformations are at the origin of the multi stability of the system, it is expected from the theory that some important features of the isothermal light-induced phase transition should be continuously light-driven, without breaking the circular symmetry of the excitation beams. We believe that our two- beam technique is not restricted to the field of liquid crystal and may be also applied in biophysics, where living entities should play the role of the non-absorbing and birefringent material.

Paper Details

Date Published: 26 June 2001
PDF: 7 pages
Proc. SPIE 4423, Nonresonant Laser-Matter Interaction (NLMI-10), (26 June 2001); doi: 10.1117/12.431239
Show Author Affiliations
Etienne Brasselet, Univ. Laval (Canada)
Tigran V. Galstian, Univ. Laval (Canada)

Published in SPIE Proceedings Vol. 4423:
Nonresonant Laser-Matter Interaction (NLMI-10)
Mikhail N. Libenson, Editor(s)

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