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

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  1. [REMOVED REF FIELD]. A. Ashkin, "Optical trapping and manipulation of neutral particles using lasers," Proc. Natl. Acad. Sci. USA 94, 4853 - 4860 (1997).
    [CrossRef] [PubMed]
  2. D. G. Grier, "A revolution in optical manipulation," Nature 424, 810-816 (2003).
    [CrossRef] [PubMed]
  3. M. E. J. Friese, T. A. Nieminen, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Optical alignment and spinning of laser-trapped microscopic particles," Nature 394, 348 - 350 (1998).
    [CrossRef]
  4. S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
    [CrossRef]
  5. S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
    [CrossRef]
  6. H. Misawa and S. Juodkazis, "Photophysics and photochemistry of a laser manipulated microparticle," Prog. Polym. Sci. 24, 665-697 (1999).
    [CrossRef]
  7. H. Aben, Photoelasticity of Glass, (Springer-Verlag, 1993).
  8. S. Juodkazis and H. Misawa, "Controlled through-hole ablation of polymer microspheres," J. Micromech. Microeng. 14, 1244-1248 (2004).
    [CrossRef]
  9. I.-C. Khoo and S.-T. Wu, Optics and Nonlinear Optics of Liquid Crystals, Vol. I (World Scientific, 1993).
  10. N. V. Tabiryan, A. V. Sukhov, and B. Y. Zel’dovich, "The orientational optical nonlinearity of liquid crystals," Mol. Cryst. Liq. Cryst. 136, 1- 9 (1986).
    [CrossRef]

2004 (1)

S. Juodkazis and H. Misawa, "Controlled through-hole ablation of polymer microspheres," J. Micromech. Microeng. 14, 1244-1248 (2004).
[CrossRef]

2003 (2)

D. G. Grier, "A revolution in optical manipulation," Nature 424, 810-816 (2003).
[CrossRef] [PubMed]

S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
[CrossRef]

1999 (2)

S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
[CrossRef]

H. Misawa and S. Juodkazis, "Photophysics and photochemistry of a laser manipulated microparticle," Prog. Polym. Sci. 24, 665-697 (1999).
[CrossRef]

1998 (1)

M. E. J. Friese, T. A. Nieminen, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Optical alignment and spinning of laser-trapped microscopic particles," Nature 394, 348 - 350 (1998).
[CrossRef]

1997 (1)

[REMOVED REF FIELD]. A. Ashkin, "Optical trapping and manipulation of neutral particles using lasers," Proc. Natl. Acad. Sci. USA 94, 4853 - 4860 (1997).
[CrossRef] [PubMed]

1986 (1)

N. V. Tabiryan, A. V. Sukhov, and B. Y. Zel’dovich, "The orientational optical nonlinearity of liquid crystals," Mol. Cryst. Liq. Cryst. 136, 1- 9 (1986).
[CrossRef]

Ashkin, A.

[REMOVED REF FIELD]. A. Ashkin, "Optical trapping and manipulation of neutral particles using lasers," Proc. Natl. Acad. Sci. USA 94, 4853 - 4860 (1997).
[CrossRef] [PubMed]

Friese, M. E. J.

M. E. J. Friese, T. A. Nieminen, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Optical alignment and spinning of laser-trapped microscopic particles," Nature 394, 348 - 350 (1998).
[CrossRef]

Grier, D. G.

D. G. Grier, "A revolution in optical manipulation," Nature 424, 810-816 (2003).
[CrossRef] [PubMed]

Hasegawa, I.

S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
[CrossRef]

Heckenberg, N. R.

M. E. J. Friese, T. A. Nieminen, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Optical alignment and spinning of laser-trapped microscopic particles," Nature 394, 348 - 350 (1998).
[CrossRef]

Juodkazis, S.

S. Juodkazis and H. Misawa, "Controlled through-hole ablation of polymer microspheres," J. Micromech. Microeng. 14, 1244-1248 (2004).
[CrossRef]

S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
[CrossRef]

H. Misawa and S. Juodkazis, "Photophysics and photochemistry of a laser manipulated microparticle," Prog. Polym. Sci. 24, 665-697 (1999).
[CrossRef]

S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
[CrossRef]

Matsuo, S.

S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
[CrossRef]

S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
[CrossRef]

Misawa, H.

S. Juodkazis and H. Misawa, "Controlled through-hole ablation of polymer microspheres," J. Micromech. Microeng. 14, 1244-1248 (2004).
[CrossRef]

S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
[CrossRef]

S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
[CrossRef]

H. Misawa and S. Juodkazis, "Photophysics and photochemistry of a laser manipulated microparticle," Prog. Polym. Sci. 24, 665-697 (1999).
[CrossRef]

Murazawa, N.

S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
[CrossRef]

Nieminen, T. A.

M. E. J. Friese, T. A. Nieminen, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Optical alignment and spinning of laser-trapped microscopic particles," Nature 394, 348 - 350 (1998).
[CrossRef]

Rubinsztein-Dunlop, H.

M. E. J. Friese, T. A. Nieminen, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Optical alignment and spinning of laser-trapped microscopic particles," Nature 394, 348 - 350 (1998).
[CrossRef]

Shikata, M.

S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
[CrossRef]

Sukhov, A. V.

N. V. Tabiryan, A. V. Sukhov, and B. Y. Zel’dovich, "The orientational optical nonlinearity of liquid crystals," Mol. Cryst. Liq. Cryst. 136, 1- 9 (1986).
[CrossRef]

Tabiryan, N. V.

N. V. Tabiryan, A. V. Sukhov, and B. Y. Zel’dovich, "The orientational optical nonlinearity of liquid crystals," Mol. Cryst. Liq. Cryst. 136, 1- 9 (1986).
[CrossRef]

Takahashi, T.

S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
[CrossRef]

Zel’dovich, B. Y.

N. V. Tabiryan, A. V. Sukhov, and B. Y. Zel’dovich, "The orientational optical nonlinearity of liquid crystals," Mol. Cryst. Liq. Cryst. 136, 1- 9 (1986).
[CrossRef]

Appl. Phys. Lett. (2)

S. Juodkazis, S. Matsuo, N. Murazawa, I. Hasegawa, and H. Misawa, "High-efficiency optical transfer of torque to a nematic liquid crystal," Appl. Phys. Lett. 82, 4657-4659 (2003).
[CrossRef]

S. Juodkazis, M. Shikata, T. Takahashi, S. Matsuo, and H. Misawa, "Fast optical swithing by a laser manipulated microdroplet of liquid crystal," Appl. Phys. Lett. 74, 3627-3629 (1999).
[CrossRef]

J. Micromech. Microeng. (1)

S. Juodkazis and H. Misawa, "Controlled through-hole ablation of polymer microspheres," J. Micromech. Microeng. 14, 1244-1248 (2004).
[CrossRef]

Mol. Cryst. Liq. Cryst. (1)

N. V. Tabiryan, A. V. Sukhov, and B. Y. Zel’dovich, "The orientational optical nonlinearity of liquid crystals," Mol. Cryst. Liq. Cryst. 136, 1- 9 (1986).
[CrossRef]

Nature (2)

D. G. Grier, "A revolution in optical manipulation," Nature 424, 810-816 (2003).
[CrossRef] [PubMed]

M. E. J. Friese, T. A. Nieminen, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Optical alignment and spinning of laser-trapped microscopic particles," Nature 394, 348 - 350 (1998).
[CrossRef]

Proc. Natl. Acad. Sci. USA (1)

[REMOVED REF FIELD]. A. Ashkin, "Optical trapping and manipulation of neutral particles using lasers," Proc. Natl. Acad. Sci. USA 94, 4853 - 4860 (1997).
[CrossRef] [PubMed]

Prog. Polym. Sci. (1)

H. Misawa and S. Juodkazis, "Photophysics and photochemistry of a laser manipulated microparticle," Prog. Polym. Sci. 24, 665-697 (1999).
[CrossRef]

Other (2)

H. Aben, Photoelasticity of Glass, (Springer-Verlag, 1993).

I.-C. Khoo and S.-T. Wu, Optics and Nonlinear Optics of Liquid Crystals, Vol. I (World Scientific, 1993).

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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.

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.

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.

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.

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 .

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