二维电介质光子晶体中量子自旋与谷霍尔效应共存的研究  

Coexistence of quantum spin and valley hall effect in two-dimensional dielectric photonic crystals

作　　者：刘香莲 李凯宙 李晓琼 张强 Liu Xiang-Lian;Li Kai-Zhou;Li Xiao-Qiong;Zhang Qiang(College of Physics and Optoelectronic Engineering,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学新型传感器与智能控制教育部重点实验室,物理与光电工程学院,山西太原030024

出　　处：《物理学报》2023年第7期224-234,共11页Acta Physica Sinica

基　　金：山西省自然科学基金(批准号:202103021224090,202103021224075);国家自然科学基金(批准号:61705159)资助的课题.

摘　　要：基于量子自旋霍尔或谷霍尔效应的拓扑光子结构具有对缺陷免疫和抑制背向散射的特性,对设计新型低损耗的光子器件起到了关键作用.本文巧妙设计了一种具有时间反演对称性的二维电介质光子晶体,实现了量子自旋霍尔效应和量子谷霍尔效应的共存.首先基于蜂巢结构排布的硅柱经过收缩扩张,打开了布里渊区Γ点的四重简并点形成拓扑平庸或非平庸的光子带隙,实现量子自旋霍尔效应.经过扩张后的蜂巢晶格演化成为Kagome结构,之后在Kagome晶格中加入正负扰动,打破光子晶体的空间反演对称性,导致布里渊区的非等价谷K和K′的简并点打开并出现完整带隙,实现了量子谷霍尔效应.数值计算结果表明,由拓扑平庸与非平庸、正扰动与负扰动的光子晶体组成的界面上可实现单向传输且对弯曲免疫的拓扑边缘态.最后,设计了基于两种效应共存的四通道系统,此系统为光学编码与稳健信号传输提供潜在方法,为电磁波的操纵提供了更大的灵活性.The location and transmission of light is the core of modern photonic integrated device,and the proposal of topological photonics provides a new way of implementing optical manipulation.Topological photonic structures based on the quantum spin hall effect or quantum valley hall effect have the properties of immunity to defects and suppress backscattering,so they play a key role in designing novel low-loss photonic devices.In this work,we design a two-dimensional dielectric photonic crystal with time-reversal symmetry to achieve the coexistence of the quantum spin hall effect and the quantum valley hall effect in a photonic crystal.The design can be likened to an electronic system in which two pairs of Kramers simplex pairs are constructed to achieve a quadruple simplex pair in a photonic crystal.First,based on the method of shrinking and expanding the silicon pillars arranged in the honeycomb structure,the quadruple degeneracy point at the Γ point of the first Brillouin zone is opened,and the corresponding topologically trivial or non-trivial photonic band gap is formed,thereby realizing quantum spin hall effect.The expanded honeycomb lattice evolves into a Kagome structure,and then positive and negative perturbations are added to the Kagome lattice,breaking the spatial inversion symmetry of the Photonic crystal.When mirror symmetry is broken,different chiral photonic crystals can be created,leading the degeneracy point of the non-equivalent valleys K and K'in the Brillouin zone to be opened and a complete band gap to appear,thus realizing the Quantum valley hall effect.In the common band gap,topologically protected edge states are induced by nontrivial valley Chern number at the interface between two photonic crystals with opposite chirality.The numerical calculations show that unidirectional transport and bending-immune topological boundary states can be realized at the interface composed of topologically trivial(non-trivial)and positively(negatively)perturbed photonic crystals.Finally,a four-channel system ba

关 键 词：光子晶体 赝自旋 谷霍尔效应 拓扑相变 

分 类 号：O734[理学—晶体学]