Optically induced angular alignment of trapped birefringent micro-objects by linearly polarized light

Higurashi, Eiji; Sawada, Renshi; Ito, Toshio

doi:10.1103/physreve.59.3676

Cited by 70 publications

(45 citation statements)

References 31 publications

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“…When a chromosome is trapped, it flips in such a way that the long arms of the two sister chromatids are no longer visible, they are oriented parallel to the direction of propagation of the light. Similar observations have been made for nonbiological elongated micro-objects (Higurashi et al 1999). When the polarization direction is changed, the chromosomes rotate accordingly (Fig.…”

Section: Resultssupporting

confidence: 82%

“…An incident beam of linear polarization becomes elliptically polarized and gains angular momentum after impinging on a birefringent particle whose optical axis is not parallel to that of the polarization of the light. The resulting change in angular momentum generates a reaction torque s on a particle with thickness d (Higurashi et al 1999):…”

Section: Theorymentioning

confidence: 99%

“…When h equals zero, the particles are aligned and no torque remains. The torque should be large enough to overcome Brownian motion in order to obtain substantial orientation; in practice, the orientation fluctuates around an equilibrium value (Higurashi et al 1999). The more the orientation deviates from the equilibrium, the larger the ''restoring torque'' becomes.…”

Section: Theorymentioning

confidence: 99%

“…By a similar mechanism (Higurashi et al 1999), circularly polarized light exerts a torque on a birefringent particle, its size being given by…”

Section: Theorymentioning

confidence: 99%

“…Whereas linearly polarized light can be used to fix the orientation of birefringent particles, circularly polarized light can make them rotate in a continuous fashion, provided that the birefringence is large enough (Friese et al 1998;Higurashi et al 1999). Elliptically polarized light, which can be regarded as a combination of linear and circular polarization, may cause a particle either to rotate continuously or to adopt a preferred orientation, depending on the degree of ellipticity of the beam.…”

Section: Introductionmentioning

confidence: 99%

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Alignment of biological microparticles by a polarized laser beam

et al. 2005

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The optical alignment of biological samples is of great relevance to microspectrometry and to the micromanipulation of single particles. Recently, Bayoudh et al. (J. Mod. Opt. 50:1581-1590 have shown that isolated, disk-shaped chloroplasts can be aligned in a controlled manner using an in-plane-polarized Gaussian beam trap, and suggested that this is due to their nonspherical shape. Here we demonstrate that the orientation of various micrometer-sized isolated biological particles, trapped by optical tweezers, can be altered in a controlled way by changing the plane of linear polarization of the tweezers. In addition to chloroplasts, we show that subchloroplast particles of small size and irregular overall shape, aggregated photosynthetic lightharvesting protein complexes as well as chromosomes can be oriented with the linearly polarized beam of the tweezers. By using a laser scanning confocal microscope equipped with a differential polarization attachment, we also measured the birefringence of magnetically oriented granal chloroplasts, and found that they exhibit strong birefringence with large local variations, which appears to originate from stacked membranes. The size and sign of the birefringence are such that the resulting anisotropic interaction with the linearly polarized laser beam significantly contributes to the torque orienting the chloroplasts.

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Section: Resultssupporting

confidence: 82%

Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

“…By a similar mechanism (Higurashi et al 1999), circularly polarized light exerts a torque on a birefringent particle, its size being given by…”

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Alignment of biological microparticles by a polarized laser beam

et al. 2005

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Optical Forces: From Fundamental to Biological Applications

et al. 2020

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Optical forces, generally arising from changes of field gradients or linear momentum carried by photons, form the basis for optical trapping and manipulation. Advances in optical forces help to reveal the nature of light–matter interactions, giving answers to a wide range of questions and solving problems across various disciplines, and are still yielding new insights in many exciting sciences, particularly in the fields of biological technology, material applications, and quantum sciences. This review focuses on recent advances in optical forces, ranging from fundamentals to applications for biological exploration. First, the basics of different types of optical forces with new light–matter interaction mechanisms and near‐field techniques for optical force generation beyond the diffraction limit with nanometer accuracy are described. Optical forces for biological applications from in vitro to in vivo are then reviewed. Applications from individual manipulation to multiple assembly into functional biophotonic probes and soft‐matter superstructures are discussed. At the end future directions for application of optical forces for biological exploration are provided.

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Nanoscale Optical Trapping: A Review

Bradac

2018

Advanced Optical Materials

118

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The First TrapIn 1969, a "back-of-the-envelope" calculation inspired Ashkin to conduct a simple experiment and determine whether it was feasible to use light radiation pressure to accelerate objects to practical speeds. Photons carry momentum hν/c (with h, ν and c being the Planck's constant, the frequency of the photon and the speed of light, respectively). If light from a source with power P shines on a mirror, P/hν photons hit the surface every second and transfer a total momentum of (2P/hν)(hν/c) = 2P/c onto it. A perfectly reflecting mirror should therefore-due to conservation-acquire an equal momentum in the same direction light propagates.Based on this crude calculation, Ashkin predicted that a light source of power P = 1 W, would produce a force (on an ideally reflecting mirror) of ≈10 nN-indeed small in absolute terms. [3] Nevertheless, if a laser beam is used as the light source and is focused on a spot of ≈1 µm 2 to hit a particle ≈1 µm in diame ter, the resulting force does become relevant. Assuming the particle is perfectly reflective and has a density of 1 g cm −3 , the calculated acceleration is ≈10 9 cm s −2 , i.e., roughly 10 6 times the acceleration of gravity. In the experiment, Ashkin conducted to test his hypotheses, [2] a cw argon laser (wavelength λ = 514.5 nm, waist radius w 0 = 6.2 µm at the focal point) was employed to accelerate latex spheres (diameter 0.59, 1.31, and 2.68 µm), which were freely suspended in water, in a glass chamber. With just milliwatts of laser power, Ashkin observed that the particles were pushed in the direction of the mildly focused Gaussian laser beam, with values for the acceleration consistent with his rough predictions. Interestingly, he also observed an unanticipated phenomenon. Particles located in the fringes of the beam were drawn toward the beam axiswhere the light intensity is the highest-before being accelerated and pushed with ≈µm s −1 speeds toward the back of the chamber. They would disperse by Brownian motion away from the beam axis once the laser was switched off, yet they would be drawn again toward the center of the beam upon turning the laser back on-as the radiation pressure had a transverse component to the force, as well as the predicted longitudinal one.The origin of both the transversal and longitudinal force is usually understood by considering two distinct regimes, depending on the relative size of the particles to the wavelength of the laser beam: the geometrical (ray optics) regime and the Rayleigh (dipole approximation) regime.Optical trapping is the craft of manipulating objects with light. Decades after its first inception in 1970, the technique has become a powerful tool for ultracold-atom physics and manipulation of micron-sized particles. Yet, optical trapping of objects at the intermediate-nanoscale-range is still beyond full grasp. This matters because the nanometric realm is where several promising advances, from mastering single-molecule experiments in biology, to fabricating hybrid devices for nanoelectronics and photonics, a...

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Optically induced angular alignment of trapped birefringent micro-objects by linearly polarized light

Cited by 70 publications

References 31 publications

Alignment of biological microparticles by a polarized laser beam

Alignment of biological microparticles by a polarized laser beam

Optical Forces: From Fundamental to Biological Applications

Nanoscale Optical Trapping: A Review

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