Optical sorting of gold nanoparticles based on the red-shift of plasmon resonance

Martin Ploschner*, Tomáš Čižmar, Michael Mazilu, Andrea Di Falco, Kishan Dholakia

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review


We present an experimental technique allowing size-based all-optical sorting of gold nanoparticles. The technique is based on the red-shift of plasmon resonance, due to retardation effects, with increasing particle size. As a result, smaller gold nanoparticles are influenced strongly by shorter wavelengths whereas larger gold nanoparticles are influenced more strongly by longer wavelengths. We utilise this retardation effect and realize sorting in a system of two counter-propagating evanescent waves, each at different wavelengths that selectively guide nanoparticles of different sizes in opposite directions. We validate this concept by demonstrating bidirectional sorting of gold nanoparticles of either 150 or 130 nm in diameter from those of 100 nm in diameter within a mixture.
Original languageEnglish
Title of host publicationProceedings of SPIE
Subtitle of host publicationOptical Trapping and Optical Micromanipulation IX
EditorsKishan Dholakia, Gabriel C. Spading
Place of PublicationBellingham, Washington
Number of pages8
ISBN (Print)9780819491756
Publication statusPublished - 2012
Externally publishedYes
EventOptical Trapping and Optical Micromanipulation IX - San Diego, California
Duration: 12 Aug 201216 Aug 2012

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceOptical Trapping and Optical Micromanipulation IX
CitySan Diego, California


  • gold nanoparticle
  • optical sorting
  • optical manipulation
  • counter-propagating geometry
  • evanescent field
  • plasmon resonance


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