Three-Dimensional Optical Trapping of a Plasmonic Nanoparticle using Low Numerical Aperture Optical Tweezers

0446101 - ÚPT 2016 RIV GB eng J - Journal Article
Brzobohatý, Oto - Šiler, Martin - Trojek, Jan - Chvátal, Lukáš - Karásek, Vítězslav - Paták, Aleš - Pokorná, Zuzana - Mika, Filip - Zemánek, Pavel
Three-Dimensional Optical Trapping of a Plasmonic Nanoparticle using Low Numerical Aperture Optical Tweezers.
Scientific Reports. Roč. 5, JAN 29 (2015), 08106:1-9. ISSN 2045-2322. E-ISSN 2045-2322
R&D Projects: GA ČR GB14-36681G
Institutional support: RVO:68081731
Keywords : discrete-dipole approximation * gold nanoparticles * radiation forces * spectroscopy
Subject RIV: BH - Optics, Masers, Lasers
Impact factor: 5.228, year: 2015

It was previously believed that larger metal nanoparticles behave as tiny mirrors that are pushed by the light beam radiative force along the direction of beam propagation, without a chance to be confined. However, several groups have recently reported successful optical trapping of gold and silver particles as large as 250 nm. We offer a possible explanation based on the fact that metal nanoparticles naturally occur in various non-spherical shapes and their optical properties differ significantly due to changes in localized plasmon excitation. We demonstrate experimentally and support theoretically three-dimensional confinement of large gold nanoparticles in an optical trap based on very low numerical aperture optics. We showed theoretically that the unique properties of gold nanoprisms allow an increase of trapping force by an order of magnitude at certain aspect ratios. These results pave the way to spatial manipulation of plasmonic nanoparticles using an optical fibre, with interesting applications in biology and medicine.
Permanent Link: http://hdl.handle.net/11104/0248067