Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
Journal Home About Issues in Progress Current Issue All Issues Feature Issues

Laser manipulation based on a light-induced molecular reordering

Naoki Murazawa, Saulius Juodkazis, and Hiroaki Misawa

Open Access Open Access

Abstract

We report on a novel principle of actuation of micrometer-sized liquid crystal droplets. It is based on a light-induced reordering of liquid crystal molecules inside the droplets. Polariscope imaging allowed to evaluate the birefringence change inside the micro-droplets. Directional actuation of the trapped droplet was achieved by cycling laser power with the direction defined by the polarization of the tweezing beam. Micro-actuation resulted from optically-induced birefringence; i.e., a nonlinear optical effect was utilized for mechanical manipulation of the micro-droplet. This principle of actuation can be used to induce molecular flows in sub-micrometer volumes.

©2006 Optical Society of America

Full Article  |  PDF Article
More Like This
Continuously rotating chiral liquid crystal droplets in a linearly polarized laser trap

Y. Yang, P. D. Brimicombe, N. W. Roberts, M. R. Dickinson, M. Osipov, and H. F. Gleeson
Opt. Express 16(10) 6877-6882 (2008)

Optical trapping of director structures and defects in liquid crystals using laser tweezers

Ivan I. Smalyukh, Daniel S. Kaputa, Aliaksandr V. Kachynski, Andrey N. Kuzmin, and Paras N. Prasad
Opt. Express 15(7) 4359-4371 (2007)

Imaging colloidal particle induced topological defects in a nematic liquid crystal using third harmonic generation microscopy

Rajesh S. Pillai, Masahito Oh-e, Hiroshi Yokoyama, G. J. Brakenhoff, and Michiel Müller
Opt. Express 14(26) 12976-12983 (2006)

View More...

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (4)
Fig. 1.
Fig. 1. Droplet of liquid crystal 5CB (radial structure) trapped at 62 (a) and 310 mW (b), respectively, in linearly (vertically) polarized laser tweezers. Diameter of droplet 5.2 μm. Circles depict approximate diameter at the focus. (c) Schematic presentation of internal molecular alignment and principle of actuation.

Download Full Size | PDF

Fig. 2.
Fig. 2. Polariscope images of the radial 5CB droplet trapped at 62 mW (a, c, e) and at 300 mW (b, d, f), respectively. Polarization is shown by arrows. The circle marks show two possible alternative laser trapping spots. Diameter of the droplet, 4.4 μm. The inset in (a) shows a simulated “Maltese” cross (Eq. 1), the intensity distribution through the crossed polarizer and analyzer with a birefringent material in between.

Download Full Size | PDF

Fig. 3.
Fig. 3. Relative (a) and absolute (b) actuation by a laser-trapped radial 5CB droplet vs. the trapping power for droplets of different diameters, D. Polarization of tweezers was linear.

Download Full Size | PDF

Fig. 4.
Fig. 4. Optical transmission images of a radial 5CB droplet observed through a pair of crossed polarizers at laser trapping power 0 (a) and 62 mW (b). Circles at points A, A’ mark the location on the droplet where transmission measurements were carried out. Arrowed line in (b) shows the polarization of the laser tweezers. A CCD camera was calibrated for a linear response.

Download Full Size | PDF

Equations (4)

Equations on this page are rendered with MathJax. Learn more.

I ( θ , Δ n ) = I 0 sin 2 ( 2 θ ) sin 2 ( π n d λ ) ,
Δθ ( z ) = 1 4 ξ 2 sin ( 2 θ ) ( d z − z 2 ) ,
n 2 ( z ) = ( Δε ) 2 sin ( 2 θ ) 2 4 K 1 c ( d z − z 2 ) .
T A − T A ′ = sin ( π d n λ ) 2 sin ( 2 θ ) 2 − sin ( π d ( n + Δ n ) λ ) 2 sin ( 2 ( θ + Δθ ) ) 2 .
Select as filters
Select Topics Cancel
Top
       
© Copyright 2024 | Optica Publishing Group. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.
Privacy | Terms of Use