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O: Fachverband Oberflächenphysik

O 63: Plasmonics and nanooptics: Applications and other aspects I

O 63.4: Vortrag

Mittwoch, 14. März 2018, 12:45–13:00, MA 041

Robustness of a nontrivial edge mode against periodic perturbations of a topological defect in a plasmonic waveguide array. — •Zlata Cherpakova and Stefan Linden — Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany

The Su-Schrieffer-Heeger (SSH) model describing a chain of identical lattice sites with alternating strong and weak bonds exhibits nontrivial edge states which are known to be robust against static deformations. Of special interest is to probe the robustness of these states against temporal perturbations. Here, we investigated the influence of periodic fluctuations on the topological edge mode in the plasmonic analogue of the SSH model. The plasmonic structures were fabricated by making use of negative-tone gray-scale electron beam lithography. Based on the quantum-optical analogy, the SSH chain was realized in an array of identical plasmonic waveguides with alternating long and short center-to-center distances. The temporal perturbations of the topological defect were implemented by periodically bending the central waveguide at the interface between two SSH domains. Surface plasmon polaritons were excited by shining a highly focused laser beam on the grating, deposited on top of the central waveguide. The spatial evolution of the SPP field intensity was monitored by real- and Fourier space leakage radiation microscopy. In our experiments as well as in numerical calculations we observe that if the frequency of these periodic perturbations was in the range which allows to overcome the bandgap, the edge mode couples to the bulk modes and becomes delocalized.