Disorder-Enabled Pure Chirality in Bilayer Plasmonic Metasurfaces

Stefan Fasold*, Sebastian Linß, Trideep Kawde, Matthias Falkner, Manuel Decker, Thomas Pertsch, Isabelle Staude

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    57 Citations (Scopus)

    Abstract

    We experimentally study the effect of rotational disorder at the unit-cell level on the optical response of chiral bilayer plasmonic metasurfaces consisting of asymmetric dimers of gold nanoantennas. The structures are fabricated based on a two-step electron-beam lithography process in combination with a precision alignment procedure. For a comprehensive characterization of the chiral optical response of the fabricated bilayer metasurfaces, we combine two different measurement strategies, namely, direct measurement of the circular transmission using circularly polarized incident light and measurement of the Jones matrix using interferometric spectroscopy with linearly polarized incident light. This allows us both to do a comprehensive analysis of the polarization dependent properties and to retrieve the effective polarization eigenstates of the metasurface in the ordered and disordered regime directly from experimental data. Our results demonstrate that rotational disorder provides a route toward chiral plasmonic metasurfaces with orthogonal, purely circular eigenstates, leading to circular dichroism and optical activity without linear birefringence. Our experimental findings are additionally complemented and verified by numerical simulations for the ordered case.

    Original languageEnglish
    Pages (from-to)1773-1778
    Number of pages6
    JournalACS Photonics
    Volume5
    Issue number5
    DOIs
    Publication statusPublished - 16 May 2018

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