• Chinese Optics Letters
  • Vol. 19, Issue 5, 052602 (2021)
Hui Liu1, Boyang Xie1, Hua Cheng1、*, Jianguo Tian1, and Shuqi Chen1、2、3、**
Author Affiliations
  • 1Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin 300071, China
  • 2Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
  • 3Collaborative Innovation Center of Light Manipulations and Applications, Shandong Normal University, Jinan 250358, China
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    Abstract

    Topological photonics provides a new opportunity for the examination of novel topological properties of matter, in which the energy band theory and ideas in topology are utilized to manipulate the propagation of photons. Since the discovery of topological insulators in condensed matter, researchers have studied similar topological effects in photonics. Topological photonics can lead to materials that support the robust unidirectional propagation of light without back reflections. This ideal transport property is unprecedented in traditional optics and may lead to radical changes in integrated optical devices. In this review, we present the exciting developments of topological photonics and focus on several prominent milestones of topological phases in photonics, such as topological insulators, topological semimetals, and higher-order topological phases. We conclude with the prospect of novel topological effects and their applications in topological photonics.

    1. Introduction

    In the last two decades, artificial microstructures including metamaterials and photonic crystals have attracted enormous interest because they provide great possibilities for manipulating optical waves. By judiciously modulating their structural parameters, the effective values of the permeability and permittivity can be designed deliberately to realize novel functionalities beyond the capability of natural materials[13]. Metamaterials are three-dimensional (3D) artificial nanostructures, which can be designed to manipulate optical waves in a specific dimension with desirable optical functionalities, such as negative refractive index[1], invisibility cloaks[3], and chiral media[4]. Metasurfaces as planar metamaterials have paved the way to arbitrarily manipulate the amplitude, polarization, phase, and frequency of optical waves in an effective way[58]. They can be widely applied in polarization conversion[9], beam deflectors[10], optical sensors[11], metalenses[12], structural colors[13], and nonlinear optics[14,15]. Photonic crystals as periodically arranged optical nanostructures with photonic band structures have become a key platform for studying optical phenomena in periodic structures. The controlling and manipulating of light in photonic crystals is based on the modulation of periodic potential, which is similar to electronic systems[16,17]. The approach to control light in periodic systems exploits photonic band structures that stem from Bragg scattering or localized resonance[18]. The photonic band structure can be designed and tuned conveniently, giving rise to potential applications in subwavelength imaging[19,20], wave transportation[21], and mimicking quantum effects[22]. Topology that characterizes the quantized global behavior of the wavefunctions on the entire band structure has aroused great interest in photonics[23].

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    Hui Liu, Boyang Xie, Hua Cheng, Jianguo Tian, Shuqi Chen. Topological photonic states in artificial microstructures [Invited][J]. Chinese Optics Letters, 2021, 19(5): 052602
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    Category: Physical Optics
    Received: Oct. 24, 2020
    Accepted: Dec. 21, 2020
    Published Online: Feb. 4, 2021
    The Author Email: Hua Cheng (hcheng@nankai.edu.cn), Shuqi Chen (schen@nankai.edu.cn)