Quantitative assessment of non-conservative radiation forces in an optical trap

Pesce, Giuseppe; Volpe, Giorgio; Luca, Anna Chiara De; Rusciano, Giulia; Volpe, Giovanni

doi:10.1209/0295-5075/86/38002

Cited by 60 publications

(68 citation statements)

References 24 publications

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“…The availability of an analytical form for φ 1 (r) will help to assess when nonequilibrium redistribution of the probability density may be ignored [27]. The first-order correction to the current density,…”

Section: Quartic Perturbation In An Anisotropic Trapmentioning

confidence: 99%

Perturbative theory for Brownian vortexes

et al. 2015

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Brownian vortexes are stochastic machines that use static non-conservative force fields to bias random thermal fluctuations into steadily circulating currents [1,2]. The archetype for this class of systems is a colloidal sphere in an optical tweezer [1,3,4]. Trapped near the focus of a strongly converging beam of light, the particle is displaced by random thermal kicks into the nonconservative part of the optical force field arising from radiation pressure [5], which then biases its diffusion [1,3]. Assuming the particle remains localized within the trap, its time-averaged trajectory traces out a toroidal vortex. Unlike trivial Brownian vortexes, such as the biased Brownian pendulum, which circulate preferentially in the direction of the bias, the general Brownian vortex can change direction and even topology in response to temperature changes. Here we introduce a theory based on a perturbative expansion of the Fokker-Planck equation for weak non-conservative driving. The first-order solution takes the form of a modified Boltzmann relation and accounts for the rich phenomenology observed in experiments on micrometer-scale colloidal spheres in optical tweezers.

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Section: Quartic Perturbation In An Anisotropic Trapmentioning

confidence: 99%

Perturbative theory for Brownian vortexes

et al. 2015

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“…One specific scheme involves a particle positioned in between a pair of misaligned beams (48). It is a part of a general class of studies in which particles are observed to undergo circulation while immersed in a static force field with nonzero curl (25,49). In addition, Angelsky et al observed orbital angular momentum transfer in circularly polarized Gaussian beams as a manifestation of the macroscopic "spin energy flow," thus confirming the theory of inhomogeneously polarized paraxial beams (34,50).…”

Section: The Evanescent Wave Technique As a Methods Of Angular Momentumentioning

confidence: 91%

Elliptical orbits of microspheres in an evanescent field

Liu

Kheifets

Ginis

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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We examine the motion of periodically driven and optically tweezed microspheres in fluid and find a rich variety of dynamic regimes. We demonstrate, in experiment and in theory, that mean particle motion in 2D is rarely parallel to the direction of the applied force and can even exhibit elliptical orbits with nonzero orbital angular momentum. The behavior is unique in that it depends neither on the nature of the microparticles nor that of the excitation; rather, angular momentum is introduced by the particle's interaction with the anisotropic fluid and optical trap environment. Overall, we find this motion to be highly tunable and predictable.optical forces | colloids | microparticles | evanescent field | elliptical motion R ecently, much work has gone into the investigation of optical forces on micro-and nanoparticles near surfaces, primarily in the context of an electric field localized by a microstructured surface (1-5).Surface-based geometries have raised theoretical excitement due to, for instance, their ability to significantly enhance optical forces (6-8) as well as the emergence of lateral forces due to the extraordinary momentum and spin in evanescent waves (9)(10)(11)(12). From an applied point of view, such geometries can enable miniaturization and parallelization of efficient optical traps enabling integration into optofluidic devices (13,14). Moreover, light-controlled microspheres near surfaces have found applications as force transducers (15-18) and pumps and switches (19,20), and in general, their collective manipulation is an advancing field (21-23).However, in the case where a microparticle is within several diameters of a surface, optical and hydrodynamic surface effects cannot be neglected. Effects arising from optical coupling or reflections can complicate trapping and detection schemes (24), and hydrodynamic interactions can cause the motion of a microparticle to become highly nontrivial (25). Despite this, little quantitative study has been done on the dynamics of optically driven particles near a surface. In studies introducing new schemes to optically manipulate matter, the particle's response function is often ignored (11,12,(26)(27)(28)(29).In this work, we investigate the dynamics of a system with both near field optical forces and surface-induced hydrodynamic effects (see Fig. 1). By driving the particle with an oscillating force from a modulated evanescent field and tracking the particle's motion closely in two dimensions, we map out a range of dynamics that can arise from the interplay of optical and hydrodynamic surface effects. We find that the magnitude and direction of the optical force depends on particle size. We also observe that the trajectory of the particle in general does not follow the direction of the force. Instead, the shape and the orientation of the trajectory vary with modulation frequency and distance of the particle from the surface, a result of the anisotropy in both the hydrodynamic drag and the optical trap spring constant.In particular, we find that under ce...

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“…For example, similar to the work of Wu et al (2009), Pesce et al (2009) also explored the non-conservative forces in optical traps.…”

Section: Applications Of Simulationsmentioning

confidence: 98%

Theory and Practice of Computational Modeling and Simulation of Optical Tweezers

Nieminen

Preez-Wilkinson

Bui

et al. 2015

Optics in the Life Sciences

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Theory and practice of simulation of optical tweezers, Journal of Quantitative Spectroscopy and Radiative Transfer, http://dx.doi.org/10.1016/j.jqsrt.2016.12.026 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractComputational modelling has made many useful contributions to the field of optical tweezers. One aspect in which it can be applied is the simulation of the dynamics of particles in optical tweezers. This can be useful for systems with many degrees of freedom, and for the simulation of experiments. While modelling of the optical force is a prerequisite for simulation of the motion of particles in optical traps, non-optical forces must also be included; the most important are usually Brownian motion and viscous drag. We discuss some applications and examples of such simulations. We review the theory and practical principles of simulation of optical tweezers, including the choice of method of calculation of optical force, numerical solution of the equations of motion of the particle, and finish with a discussion of a range of open problems.

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Quantitative assessment of non-conservative radiation forces in an optical trap

Cited by 60 publications

References 24 publications

Perturbative theory for Brownian vortexes

Perturbative theory for Brownian vortexes

Elliptical orbits of microspheres in an evanescent field

Theory and Practice of Computational Modeling and Simulation of Optical Tweezers

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