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arXiv · 1703.04570

Direct Observation of Valley-polarized Topological Edge States in Designer Surface Plasmon Crystals

Xiaoxiao Wu·Yang Meng·Jingxuan Tian·Yingzhou Huang·Hong Xiang·Dezhuan Han·Weijia Wen
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Abstract

The extensive research of two-dimensional layered materials has revealed that valleys, as energy extrema in momentum space, could offer a new degree of freedom for carrying information. Based on this concept, researchers have predicted valley-Hall topological insulators which could support valley-polarized edge states at non-trivial domain walls. Recently, several kinds of photonic or sonic crystals have been proposed as classical counterparts of valley-Hall topological insulators. However, direct experimental observation of valley-polarized edge states in photonic crystals is still difficult until now. Here, we demonstrate a designer surface plasmon crystal comprising metallic patterns deposited on a dielectric substrate, which can become a valley-Hall photonic topological insulator by exploiting the mirror-symmetry-breaking mechanism. Topological edge states with valley-dependent transport are directly visualized in the microwave regime. The observed edge states are confirmed to be fully valley-polarized through spatial Fourier transforms. Topological protection of the edge states at sharp corners is also experimentally demonstrated.

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Xiaoxiao Wu, Yang Meng, Jingxuan Tian, Yingzhou Huang, Hong Xiang, Dezhuan Han, Weijia Wen. 2017-03-14. Direct Observation of Valley-polarized Topological Edge States in Designer Surface Plasmon Crystals. https://doi.org/10.1038/s41467-017-01515-2

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