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Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 14, Iss. 23 — Nov. 13, 2006
  • pp: 11433–11441

High-frequency dielectric relaxation of liquid crystals: THz time-domain spectroscopy of liquid crystal colloids

Masahito Oh-e, Hiroshi Yokoyama, Mattijs Koeberg, Euan Hendry, and Mischa Bonn  »View Author Affiliations

Optics Express, Vol. 14, Issue 23, pp. 11433-11441 (2006)

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Terahertz time-domain spectroscopy has been used to study the dielectric relaxation of pure 4’-n-pentyl-4-cyanobiphenyl (5CB) liquid crystal (LC) and its mixtures with 10 µm SiO2 particles in the frequency range 0.2–2 THz. For the pure sample, we find that spatial inhomogeneities consisting of oriented domains, comparable in size to our probe area (~1 mm2), cause a large scatter in the measured dielectric function, due to varying contributions from the ordinary and extraordinary components. In the LC/particle mixtures, ordering of the LC at the surface of the SiO2 particles results in a break-up of these domains, giving rise to a spatially much more homogeneous dielectric response. The inferred dielectric function can be interpreted using effective medium theory and the Debye relaxation model. We observe this stabilizing effect for interparticle distances < ~30 µm, setting a lower limit for the size of oriented domains in the bulk LC.

© 2006 Optical Society of America

OCIS Codes
(160.3710) Materials : Liquid crystals
(160.6030) Materials : Silica
(300.6250) Spectroscopy : Spectroscopy, condensed matter
(300.6270) Spectroscopy : Spectroscopy, far infrared
(320.7150) Ultrafast optics : Ultrafast spectroscopy

ToC Category:

Original Manuscript: September 1, 2006
Revised Manuscript: October 26, 2006
Manuscript Accepted: October 30, 2006
Published: November 13, 2006

Masahito Oh-e, Hiroshi Yokoyama, Mattijs Koeberg, Euan Hendry, and Mischa Bonn, "High-frequency dielectric relaxation of liquid crystals: THz time-domain spectroscopy of liquid crystal colloids," Opt. Express 14, 11433-11441 (2006)

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