Original Article

Citation: Light: Science & Applications (2017) 6, e16258; doi:10.1038/lsa.2016.258
Published online 5 May 2017

Plasmon-assisted optical trapping and anti-trapping
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Aliaksandra Ivinskaya1, Mihail I Petrov1, Andrey A Bogdanov1, Ivan Shishkin2, Pavel Ginzburg1,2 and Alexander S Shalin1,3,4

  1. 1Department of Nanophotonics and Metamaterials, ITMO University, Birzhevaja Line, 14, 199034 St Petersburg, Russia
  2. 2School of Electrical Engineering, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
  3. 3Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences (Ulyanovsk branch), Goncharova Street 48/2, 432071 Ulyanovsk, Russia
  4. 4Ulyanovsk State University, Lev Tolstoy Street 42, 432017 Ulyanovsk, Russia

Correspondence: AS Shalin, Email: alexandesh@gmail.com

Received 12 July 2016; Revised 26 October 2016; Accepted 23 November 2016
Accepted article preview online 28 November 2016

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Abstract

The ability to manipulate small objects with focused laser beams has opened a venue for investigating dynamical phenomena relevant to both fundamental and applied science. Nanophotonic and plasmonic structures enable superior performance in optical trapping via highly confined near-fields. In this case, the interplay between the excitation field, re-scattered fields and the eigenmodes of a structure can lead to remarkable effects; one such effect, as reported here, is particle trapping by laser light in a vicinity of metal surface. Surface plasmon excitation at the metal substrate plays a key role in tailoring the optical forces acting on a nearby particle. Depending on whether the illuminating Gaussian beam is focused above or below the metal-dielectric interface, an order-of-magnitude enhancement or reduction of the trap stiffness is achieved compared with that of standard glass substrates. Furthermore, a novel plasmon-assisted anti-trapping effect (particle repulsion from the beam axis) is predicted and studied. A highly accurate particle sorting scheme based on the new anti-trapping effect is analyzed. The ability to distinguish and configure various electromagnetic channels through the developed analytical theory provides guidelines for designing auxiliary nanostructures and achieving ultimate control over mechanical motion at the micro- and nano-scales.

Keywords:

Gaussian beam; Green’s function; optical forces; optical tweezers; surface plasmon

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