Interaction of edge exciton polaritons with engineered defects in the hyperbolic material Bi2Se3
Robin Lingstädt, Nahid Talebi, Mario Hentschel, Soudabeh Mashhadi, Bruno Gompf, Marko Burghard, Harald Gießen, Peter A. van Aken
Abstract
Abstract Hyperbolic materials exhibit unique properties that enable intriguing applications in nanophotonics. The topological insulator Bi 2 Se 3 represents a natural hyperbolic optical medium, both in the THz and visible range. Here, using cathodoluminescence spectroscopy and electron energy-loss spectroscopy, we demonstrate that Bi 2 Se 3 supports room-temperature exciton polaritons and explore the behavior of hyperbolic edge exciton polaritons, which are hybrid modes resulting from the coupling of the polaritons bound to the upper and lower edges of Bi 2 Se 3 nanoplatelets. We compare Fabry-Pérot-like resonances emerging in edge polariton propagation along pristine and artificially structured edges and experimentally demonstrate the possibility to steer edge polaritons by means of grooves and nanocavities. The observed scattering of edge polaritons by defect structures is found to be in good agreement with finite-difference time-domain simulations. Our findings reveal the extraordinary capability of hyperbolic polariton propagation to cope with the presence of defects, providing an excellent basis for applications such as nanooptical circuitry, nanoscale cloaking and nanoscopic quantum technology.