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Proceedings Paper

Dynamics of optically bound clusters (Conference Presentation)

Paper Abstract

Optical binding was first observed between spherical particles around thirty years ago. Optical binding forces can result in various geometric arrangements of colloidal matter into regular, crystalline arrays and can induce complex, non-conservative and quasi-periodic motions. Although most studies of optical binding have focussed on dielectric spheres, recent departures from this trend have included silver bipyramids, nanowires and chiral particles. With reduction of particle symmetry comes extra complexity: torques can be applied to non-spherical objects by the applied beam, as well as by the scattered field from neighbouring particles. Another way to lower the symmetry of the system is if optical binding itself results in the formation of a lower symmetry cluster. The resulting cluster may then interact with the angular momentum of the beam, generating non-conservative, quasi-cyclic motion. When large numbers of particles are present in the optical trap, the precise natures of the motions become hard to predict. In this paper, we present the results of computer simulations used to explore the dynamical behavior of optically bound clusters of spherical nanoparticles, in beams possessing both spin and orbital angular momentum. While some of the behaviour observed has previously been predicted for low-symmetry shaped and chiral nanoparticles, the use of spheres enables a deeper understanding of the processes underlying the dynamics obtained. The diverse complex motion possible will be explored for a variety of homogeneous and heterogeneous optical fields, with sufficiently large numbers of particles to explore the possibilities of optically driven swarms.

Paper Details

Date Published: 9 September 2019
Proc. SPIE 11083, Optical Trapping and Optical Micromanipulation XVI, 1108328 (9 September 2019); doi: 10.1117/12.2531276
Show Author Affiliations
Simon Hanna, Univ. of Bristol (United Kingdom)
Chaoyi Zhang, Univ. of Bristol (United Kingdom)

Published in SPIE Proceedings Vol. 11083:
Optical Trapping and Optical Micromanipulation XVI
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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