Femtosecond pulse-width dependent trapping and directional ejection dynamics of dielectric nanoparticles

Wei Yi Chiang, Anwar Usman*, Hiroshi Masuhara

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

We demonstrate that laser pulse duration, which determines its impulsive peak power, is an effective parameter to control the number of optically trapped dielectric nanoparticles, their ejections along the directions perpendicular to polarization vector, and their migration distances from the trapping site. This ability to controllably confine and eject the nanoparticle is explained by pulse width-dependent optical forces exerted on nanoparticles in the trapping site and ratio between the repulsive and attractive forces. We also show that the directional ejections occur only when the number of nanoparticles confined in the trapping site exceeds a definite threshold. We interpret our data by considering the formation of transient assembly of the optically confined nanoparticles, partial ejection of the assembly, and subsequent filling of the trapping site. The understanding of optical trapping and directional ejections by ultrashort laser pulses paves the way to optically controlled manipulation and sorting of nanoparticles.

Original languageEnglish
Pages (from-to)19182-19188
Number of pages7
JournalJournal of Physical Chemistry C
Volume117
Issue number37
DOIs
StatePublished - 19 Sep 2013

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