Chiroptical transmission through a plasmonic helical traveling-wave nanoantenna, towards on-tip chiroptical probes

This is the authors' abstract. We don't add key points for this paper.

Resonant plasmonic helices have been widely utilized for locally enhancing and tailoring optical chirality. Here we investigate their nonresonant operation through the recently introduced concept of a plasmonic helical "traveling-wave" nanoantenna. Relying on the coupling of a nonresonant plasmonic helix and a nano-aperture, the helical traveling-wave nanoantenna transmits circularly polarized light with the same handedness as the helix and blocks the other, with a measured dissymmetry factor larger than 1.92 (maximum value of 2). This chiroptical transmission is spatially localized, spectrally broadband, and background-free. Finally, we demonstrate the possibility to engineer such a plasmonic helical nanoantenna at the apex of a sharp tip typically used in scanning near-field microscopies, thus opening the route for moveable, broadband, and background-free chiroptical probes.