Light-induced rotation of dye-doped liquid crystal droplets

C. Manzo, D. Paparo, L. Marrucci, I. Jánossy

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

We investigate both theoretically and experimentally the rotational dynamics of micrometric droplets of dye-doped and pure liquid crystal induced by circularly and elliptically polarized laser light. The droplets are dispersed in water and trapped in the focus of the laser beam. Since the optical torque acting on the molecular director is known to be strongly enhanced in light-absorbing dye-doped materials, the question arises whether a similar enhancement takes place also for the overall optical torque acting on the whole droplets. We searched for such enhancement by measuring and comparing the rotation speed of dye-doped droplets induced by a laser beam having a wavelength either inside or outside the dye absorption band, and also comparing it with the rotation of pure liquid crystal droplets. No enhancement was found, confirming that photoinduced dye effects are only associated with an internal exchange of angular momentum between orientational and translational degrees of freedom of matter. Our result provides also direct experimental proof of the existence of a photoinduced stress tensor in the illuminated dye-doped liquid crystal. Finally, peculiar photoinduced dynamical effects are predicted to occur in droplets in which the molecular director is not rigidly locked to the flow, but so far they could not be observed.

Original languageEnglish
Article number051707
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume73
Issue number5
DOIs
Publication statusPublished - 2006

Fingerprint

Dyes
doped crystals
Droplet
Liquid Crystal
dyes
liquid crystals
Enhancement
Laser Beam
Torque
torque
augmentation
laser beams
Stress Tensor
stress tensors
Angular Momentum
Absorbing
Absorption
angular momentum
degrees of freedom
Degree of freedom

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Condensed Matter Physics
  • Statistical and Nonlinear Physics
  • Mathematical Physics

Cite this

Light-induced rotation of dye-doped liquid crystal droplets. / Manzo, C.; Paparo, D.; Marrucci, L.; Jánossy, I.

In: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, Vol. 73, No. 5, 051707, 2006.

Research output: Contribution to journalArticle

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