Three-dimensional arrays of submicron particles generated by a four-beam optical lattice

Slama-Eliau, B. N.; Raithel, Georg

doi:10.1103/physreve.83.051406

Cited by 14 publications

(20 citation statements)

References 25 publications

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“…The resulting trapping potentials are close to those explicitly provided in Ref. [18] for the case φ = 45 o . With the lattice turned off, diffusion is by far the dominant source of motion and gravity is negligible (it takes the particles about one day to accumulate near the bottom of the cell).…”

Section: Setupsupporting

confidence: 85%

“…Optical forces on polystyrene particles in aqueous solution are gener-ated by four intersecting, mutually-coherent laser beams that generate a 3D interference pattern, a method we presented in Ref. [18]. The optical setup is sketched in Fig.…”

Section: Physical Conceptsmentioning

confidence: 99%

“…The 3D optical lattice is generated using four beams derived from a single laser (air wavelength λ 0 = 1064 nm, line-width < 1 MHz) similar to the setup described in [18]. As illustrated in Fig.…”

Section: Setupmentioning

confidence: 99%

“…Sometimes auxiliary normal forces from sample cell boundaries are used. In the present work, we employ a radiationpressure-balanced optical lattice formed by four 1064 nm laser beams that intersect at a confocal point [18]. The optical lattice generates a three-dimensional (3D) array of periodic traps for sub-micron polystyrene spheres (refractive index n p = 1.59, diameter ∼ 200 nm).…”

mentioning

confidence: 99%

“…Direct visual observation of the crystal formation [18] indicates that the crystallization dynamics as well as the degree of particle localization are driven by the competition between Brownian motion and the forces induced by the optical trapping potentials. A quantitative understanding of Brownian motion effects represents an important prerequisite to applications of optically induced crystals of sub-micron particles in solution.…”

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confidence: 99%

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Bragg scattering and Brownian motion dynamics in optically induced crystals of submicron particles

2013

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A set of four confocal laser beams of 1064 nm wavelength is used to prepare optically induced crystals of sub-micron particles in aqueous solution. Thousands of polystyrene spheres of about 200 nm diameter are trapped in three dimensions. Bragg scattering patterns obtained with a probe beam of 532 nm wavelength are in agreement with the calculated lattice structure and its polarization dependence. The decay and rise of the Bragg scattering intensity upon switching the lattice off and on reveals the Brownian motion dynamics of the particles in the periodic optical trapping potential. Experimental results agree well with results from trajectory simulations based on the Langevin equation. The results exhibit the interplay between Brownian motion and deterministic forces in an inhomogeneous (near-)periodic optical trapping potential.

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Section: Setupsupporting

confidence: 85%

Section: Physical Conceptsmentioning

confidence: 99%

Section: Setupmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Bragg scattering and Brownian motion dynamics in optically induced crystals of submicron particles

2013

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Nanoscale Optical Trapping: A Review

Bradac

2018

Advanced Optical Materials

115

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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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Self-Organization of Metal Nanoparticles in Light: Electrodynamics–Molecular Dynamics Simulations and Optical Binding Experiments

McCormack

Han

Yan

2018

J. Phys. Chem. Lett.

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Light-driven self-organization of metal nanoparticles (NPs) can lead to unique optical matter systems, yet simulation of such self-organization (i.e., optical binding) is a complex computational problem that increases nonlinearly with system size. Here we show that a combined electrodynamics-molecular dynamics simulation technique can simulate the trajectories and predict stable configurations of silver NPs in optical fields. The simulated dynamic equilibrium of a two-NP system matches the probability density of oscillations for two optically bound NPs obtained experimentally. The predicted stable configurations for up to eight NPs are further compared to experimental observations of silver NP clusters formed by optical binding in a Bessel beam. All configurations are confirmed to form in real systems, including pentagonal clusters with five-fold symmetry. Our combined simulations and experiments have revealed a diverse optical matter system formed by anisotropic optical binding interactions, providing a new strategy to discover artificial materials.

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Three-dimensional arrays of submicron particles generated by a four-beam optical lattice

Cited by 14 publications

References 25 publications

Bragg scattering and Brownian motion dynamics in optically induced crystals of submicron particles

Bragg scattering and Brownian motion dynamics in optically induced crystals of submicron particles

Nanoscale Optical Trapping: A Review

Self-Organization of Metal Nanoparticles in Light: Electrodynamics–Molecular Dynamics Simulations and Optical Binding Experiments

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