Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 19: Plasmonics and Nanooptics II

O 19.6: Talk

Monday, March 11, 2013, 17:15–17:30, H31

Large-area 3D chiral plasmonic nanostructures fabricated by colloidal hole mask nanolithography — •Bettina Frank, Jun Zhao, and Harald Giessen — 4th Physics Institute and Research Center SCoPE, University of Stuttgart, Germany

We fabricate large-area (square centimeter size) 3D chiral plasmonic nanostructures using colloidal hole mask lithography [1]. We rotate the sample in a polar direction and change the speed of the rotation. Hence, the evaporated amount of metal through the gold holes changes as a function of polar angle. This leads to ramp-like structures and yields true 3D chirality. Additionally, we fabricate a 3D chiral ramp of MgF2 and evaporate a flat strip of gold on top of it. By changing the polar rotation direction, left- as well as right-handed enantiomers can be manufactured. Measuring the transmittance upon circularly polarized light and applying the rules of Hentschel et al. to determine circular dichroism if the sample does not exhibit C3 or C4 symmetry [2], we find a strong chiral optical response with several resonances in the near-infrared between 1 and 3 micrometer wavelength. We are able to interpret this response with the aid of the fundamental modes of the split-ring resonators. Our structures will be very useful for large-area thin-film chiroptical elements and for plasmonic chiral enantiomer sensors.

[1] S. Cataldo et al., ACS Nano 6, 979 (2012).

[2] M. Hentschel et al., Nano Lett 12, 2542 (2012), supplement.