Photonic Floquet topological insulators in a fractal lattice

Zhaoju Yang; Eran Lustig; Yaakov Lumer; Mordechai Segev

doi:10.1038/s41377-020-00354-z

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Photonic Floquet topological insulators in a fractal lattice

Article

- Photonic Floquet topological insulators in a fractal lattice
- Light: Science & Applications Vol. 9, Issue 4, Pages: 1246-1252(2020)
- Affiliations：
  
  Physics Department and Solid State Institute, Technion–Israel Institute of Technology, Haifa 32000, Israel
- Author bio：
  
  Mordechai Segev (msegev@technion.ac.il)
- Funds：
- DOI：10.1038/s41377-020-00354-z
  CLC：
- Published：2020，
  
  Published Online：20 July 2020，
  
  Received：07 April 2020，
  
  Revised：11 June 2020，
  
  Accepted：18 June 2020
- Accepted：
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Yang, Z. et al. Photonic Floquet topological insulators in a fractal lattice. Light: Science & Applications, 9, 1246-1252 (2020).
DOI：

Yang, Z. et al. Photonic Floquet topological insulators in a fractal lattice. Light: Science & Applications, 9, 1246-1252 (2020). DOI： 10.1038/s41377-020-00354-z.

摘要

Abstract

We present Floquet fractal topological insulators: photonic topological insulators in a fractal-dimensional lattice consisting of helical waveguides. The helical modulation induces an artificial gauge field and leads to a trivial-to-topological phase transition. The quasi-energy spectrum shows the existence of topological edge states corresponding to real-space Chern number 1. We study the propagation of light along the outer edges of the fractal lattice and find that wavepackets move along the edges without penetrating into the bulk or backscattering even in the presence of disorder. In a similar vein

we find that the inner edges of the fractal lattice also exhibit robust transport when the fractal is of sufficiently high generation. Finally

we find topological edge states that span the circumference of a hybrid half-fractal

half-honeycomb lattice

passing from the edge of the honeycomb lattice to the edge of the fractal structure virtually without scattering

despite the transition from two dimensions to a fractal dimension. Our system offers a realizable experimental platform to study topological fractals and provides new directions for exploring topological physics.

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references

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