Dresden 2017 – scientific programme
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O: Fachverband Oberflächenphysik
O 76: Plasmonics and Nanooptics VII: Applications and Other Aspects
O 76.6: Talk
Wednesday, March 22, 2017, 16:15–16:30, TRE Ma
Spectral imaging of topologically protected edge states in plasmonic waveguide arrays — •Felix Bleckmann1, Andrea Alberti2, and Stefan Linden1 — 1Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universität Bonn, Nußallee 12, 53115 Bonn, Germany — 2Institut für Angewandte Physik, Rheinische Friedrich-Wilhelms-Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany.
The Su-Schrieffer-Heeger (SSH) model, i.e., a chain of lattice sites coupled via alternating strong and weak bonds, is the prototypical one-dimensional system with nontrivial topological character. It supports two different dimerizations with distinct topological properties. At any interface between both, one topologically protected edge state exists.
We report on the observation of topologically protected edge states in evanescently coupled plasmonic waveguide arrays employed to implement the SSH model. The arrays are fabricated on top of a gold film by negative-tone grey-scale electron-beam lithography. Alternating strong and weak bonds were realized by choosing two different separations between neighboring plasmonic waveguides. We created an interface between the two dimerizations of the SSH model by repeating the larger separation twice.
Surface plasmon polaritons are excited directly at the interface. Their spatial evolution as well as their momentum-resolved spectra are measured by making use of real and Fourier space leakage radiation microscopy. We demonstrate that the topologically protected edge state is localized at the interface and has a midgap position in the momentum-resolved spectrum.