Mechanical effect of photonic spin-orbit interaction for a metallic nanohelix

Jun Chen, Shubo Wang, Xiao Li, Tsz Fai Jack Ng*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

12 Citations (Scopus)


Upon illumination by a circularly polarized plane wave, a nanohelix converts part of the incoming optical spin angular momentum into optical orbital angular momentum. Here, by combining partial wave analysis with band structure and eigenmode calculations, we studied the optical torque and light extinction for a gold nanohelix. It is found that spin-orbital angular momentum conversion is a necessary condition for inducing recoil optical torque, but not for light extinction. In other words, a particle can have a large light extinction cross section but not a strong torque, or vice versa. Our calculation also shows that broad frequency band negative optical torque can also exist in a nanohelix, which possesses screw-axis symmetry.

Original languageEnglish
Pages (from-to)27694-27704
Number of pages11
JournalOptics Express
Issue number21
Publication statusPublished - 15 Oct 2018

Scopus Subject Areas

  • Atomic and Molecular Physics, and Optics


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