Direct Observation of Corner States in Second-Order Topological Photonic Crystal Slabs

Xiao-Dong Chen, Wei-Min Deng, Fu-Long Shi, Fu-Li Zhao, Min Chen, and Jian-Wen Dong
Phys. Rev. Lett. 122, 233902 – Published 14 June 2019
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Abstract

Recently, higher-order topological phases that do not obey the usual bulk-edge correspondence principle have been introduced in electronic insulators and brought into classical systems, featuring in-gap corner or hinge states. In this Letter, using near-field scanning measurements, we show the direct observation of corner states in second-order topological photonic crystal slabs consisting of periodic dielectric rods on a perfect electric conductor. Based on the generalized two-dimensional Su-Schrieffer-Heeger model, we show that the emergence of corner states roots in the nonzero edge dipolar polarization instead of the nonzero bulk quadrupole polarization. We demonstrate the topological transition of two-dimensional Zak phases of photonic crystal slabs by tuning intracell distances between two neighboring rods. We also directly observe in-gap one-dimensional edge states and zero-dimensional corner states in the microwave regime. Our work presents that the photonic crystal slab is a powerful platform to directly observe topological states and paves the way to study higher-order photonic topological insulators.

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  • Received 19 December 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.233902

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & Optical

Authors & Affiliations

Xiao-Dong Chen, Wei-Min Deng, Fu-Long Shi, Fu-Li Zhao, Min Chen, and Jian-Wen Dong*

  • School of Physics and State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, China

  • *Corresponding author. dongjwen@mail.sysu.edu.cn
  • X.-D. C., W.-M. D., and F.-L. S. contributed equally to this work.

See Also

Visualization of Higher-Order Topological Insulating Phases in Two-Dimensional Dielectric Photonic Crystals

Bi-Ye Xie, Guang-Xu Su, Hong-Fei Wang, Hai Su, Xiao-Peng Shen, Peng Zhan, Ming-Hui Lu, Zhen-Lin Wang, and Yan-Feng Chen
Phys. Rev. Lett. 122, 233903 (2019)

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Issue

Vol. 122, Iss. 23 — 14 June 2019

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