Colloidal density control with Bessel\u2013Gauss beams

Cristian Hernando Acevedo,Aristide Dogariu,Ruitao Wu,Eric G Johnson,J Keith Miller

doi:10.1038/s41598-021-91638-w

Cristian Hernando Acevedo, Aristide Dogariu + Show 3 more

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https://doi.org/10.1038/s41598-021-91638-w

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Abstract

Optical manipulation of colloidal systems is of high interest for both fundamental studies and practical applications. It has been shown that optically induced thermophoresis and nonlinear interactions can significantly affect the properties of dense colloidal media. However, macroscopic scale phenomena can also be generated at thermal equilibrium. Here, we demonstrate that steady-state variations of particle density can be created over large, three-dimensional regions by appropriately structured external optical fields. We prove analytically and experimentally that an optical vortex beam can dynamically control the spatial density of microscopic particles along the direction of its propagation. We show that these artificial steady-states can be generated at will and can be maintained indefinitely, which can be beneficial for applications such as path clearing and mass transportation.

Highlights

Optical manipulation of colloidal systems is of high interest for both fundamental studies and practical applications
The internal dynamics of the colloidal system can be described in terms of a directional flux that points along the direction of the local velocity field u(r, t)
Theoretically and experimentally, that an optical vortex beam can be used to control the density of nanometric particles in a colloidal system

Summary

Introduction

Optical manipulation of colloidal systems is of high interest for both fundamental studies and practical applications. We prove analytically and experimentally that an optical vortex beam can dynamically control the spatial density of microscopic particles along the direction of its propagation. We show that these artificial steady-states can be generated at will and can be maintained indefinitely, which can be beneficial for applications such as path clearing and mass transportation. Colloidal systems comprising particulates of varying sizes, from atomic to macroscopic scales, have unique spatial and temporal characteristics that are central to phenomena in chemistry, biology, environmental science, materials science, etc Dynamic control of their properties is critical for a variety of applications. A dynamic alteration of the optical transmittance through a colloidal medium has been p roposed[39]

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