Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 59: Plasmonics and Nanooptics

O 59.3: Poster

Dienstag, 21. März 2017, 18:30–20:30, P2-OG1

Near Field Investigation of Plasmonic Bowtie Antennas — •Jon Polensky, Bendix Ketelsen, Thomas Klings, Jens Ehlermann, Irene Fernandez-Cuesta, and Robert Blick — Center for Hybrid Nanostructures (CHyN), Hamburg, Germany

Single-molecule detection techniques are revolutionizing the way we understand (bio)chemical processes. But observing single molecules is a big technological challenge. One idea is using the hot-spot yielded by a plasmonic nanoantenna which confines and enhances optical fields. The hot spot can be focused down to less than tens of nanometers.

We have constructed a Scanning Near Field Optical Microscope (SNOM) to investigate the optical near fields of relevant structures. One proof of concept is the study of the optical properties of the aforementioned plasmonic nanoantennas. Two different geometries were characterized and compared. We used the SNOM to measure the intensity of the hotspot by changing the polarization of the incident laser beam.

We investigated triangular and circular antennas made of gold, with triangle side lengths of l = 140 nm and a radius of r = 80 nm, respectively. The antennas were made by nanoimprint lithography and lift-off. It was found out, that both antenna shapes lead to a field enhancement in the nanometric gap between the structures. The polarization change of the incident beam showed a significant effect: light that is parallel polarized to the long axis of the antenna induced a more intense hotspot than perpendicular polarized light. The factor between the two relative hotpot intensities is 1.5.