Broadband spin-controlled focusing via logarithmic-spiral nanoslits of varying width

M. Q. Mehmood, Hong Liu, Kun Huang, Shengtao Mei, Aaron Danner, Boris Luk'yanchuk, Shuang Zhang, Jinghua Teng, Stefan A. Maier, Cheng-wei Qiu

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12 Citations (Scopus)
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This work presents analytical, numerical and experimental demonstrations of light diffracted through a logarithmic spiral (LS) nanoslit, which forms a type of switchable and focus-tunable structure. Owing to a strong dependence on the incident photon spin, the proposed LS-nanoslit converges incoming light of opposite handedness (to that of the LS-nanoslit) into a confined subwavelength spot, while it shapes light with similar chirality into a donut-like intensity profile. Benefitting from the varying width of the LS-nanoslit, different incident wavelengths interfere constructively at different positions, i.e., the focal length shifts from 7.5 μm (at λ = 632.8 nm) to 10 μm (at λ = 488 nm), which opens up new opportunities for tuning and spatially separating broadband light at the micrometer scale.
Original languageEnglish
Pages (from-to)674–681
JournalLaser and Photonics Reviews
Issue number6
Early online date19 Sept 2015
Publication statusPublished - 24 Nov 2015


  • logarithmic-spiral nanoslit
  • confined spot
  • diffraction
  • broadband spin-controlled focusing


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