Bidirectional Optical Sorting of Gold Nanoparticles

Martin Ploschner, Tomas Cizmar, Michael Mazilu, Andrea Di Falco, Kishan Dholakia

Research output: Contribution to journalArticlepeer-review

94 Citations (Scopus)


We present a generic technique allowing size-based all-optical sorting of gold nanoparticles. Optical forces acting on metallic nanoparticles are substantially enhanced when they are illuminated at a wavelength near the plasmon resonance, as determined by the particle’s geometry. Exploiting these resonances, we 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
Pages (from-to)1923-1927
Number of pages5
JournalNano Letters
Issue number4
Publication statusPublished - 26 Mar 2012


  • Gold nanoparticle
  • optical sorting
  • optical manipulation
  • counter-propagating geometry
  • plasmon resonance


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