Selective trapping or rotation of isotropic dielectric microparticles by optical near field in a plasmonic archimedes spiral.

Tsai, Wei-Yi; Huang, Jer-Shing; Huang, Chen-Bin · Nano Lett · 2014

basic_science · Level V

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Abstract

We demonstrate selective trapping or rotation of optically isotropic dielectric microparticles by plasmonic near field in a single gold plasmonic Archimedes spiral. Depending on the handedness of circularly polarized excitation, plasmonic near fields can be selectively engineered into either a focusing spot for particle trapping or a plasmonic vortex for particle rotation. Our design provides a simple solution for subwavelength optical manipulation and may find applications in micromechanical and microfluidic systems.