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Proceedings Paper

Optimal trapping beam for spherical micro-particles (Conference Presentation)
Author(s): Michael Mazilu

Paper Abstract

Scattering is one of the simplest light mater interactions possible. For spherical particles, this process can be described using the Lorenz-Mie theory, which makes use of vector spherical harmonic solutions of Maxwell’s equations to represent the fields involved. Using these solutions it is possible to describe the light field scattered from microscopic spherical particles and thus represent the field around a scattering object as a function of the incident fields. These solutions also allow us to determine the optical momentum transfer to the scattering object. This can be calculated using Maxwell stress tensor. Here, we use this approach to calculate the quadratic relationship between the incident field and the optical forces acting on the scattering objects. This relationship defines also a set of orthogonal optical eigenmodes, which delivers a natural basis to describe momentum transfer in light-matter interactions. Using this natural description of the momentum transfer it is possible to define, for each numerical aperture, particle size or geometry the optimal trapping beam in 1, 2 or 3 dimensions. We present a study as a function of the particle parameter and conclude on the maximum achievable trapping stiffness enhancement factor as a function of these parameters.

Paper Details

Date Published: 19 September 2017
Proc. SPIE 10347, Optical Trapping and Optical Micromanipulation XIV, 103470M (19 September 2017); doi: 10.1117/12.2271741
Show Author Affiliations
Michael Mazilu, Univ. of St. Andrews (United Kingdom)

Published in SPIE Proceedings Vol. 10347:
Optical Trapping and Optical Micromanipulation XIV
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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