Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 30: Plasmonics and Nanooptics III

O 30.2: Vortrag

Dienstag, 12. März 2013, 10:45–11:00, H31

Coupled plasmonic waveguide arrays — •Alexander Block, Felix Bleckmann, and Stefan Linden — Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn

Surface plasmon polaritons (SPPs) are hybrid electromagnetic waves propagating along a metal-dielectric interface. Their effective refractive index can be controlled by adding an additional dielectric on top of the metal. Varying the thickness of the dielectric layer allows us to fabricate structures with complex refractive index profiles. Here, we use negative-tone gray-scale electron beam lithography to define waveguide arrays made of PMMA on top of a gold film.

In our experiment SPPs are excited by focusing laser light onto a grating coupler and the resulting SPP propagation can be visualized by imaging the leakage radiation with a high numerical aperture objective. In contrast to other studies on coupled waveguide arrays our setup can directly observe the field intensities inside the waveguides. The results clearly show the coupling between the waveguides as predicted by the coupled mode theory. The coupling constant can be obtained as a function of the waveguides' thickness and their separation. These results agree well with finite element simulations which are also presented.