Broadband photonic topological insulator based on triangular-holes array with higher energy filling efficiency

Nanophotonics

article

Zhishen Zhang¹  Feng Li¹  Jiuyang Lu¹  Tao Liu³  Xiaobo Heng¹  Yongcheng He²  Haohua Liang²  Jiulin Gan²  Zhongmin Yang¹ 

[1] School of Physics and Optoelectronic Technology, South China University of Technology;State Key Laboratory Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology;Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research

关键词: broadband photonic crystals;    valley photonic crystals;    photonic topological insulators;   

DOI  :  10.1515/nanoph-2020-0086

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

Photonic topological insulators (PTIs) bring markedly new opportunities to photonic devices with low dissipation and directional transmission of signal over a wide wavelength range due to the broadband topological protection. However, the maximum gap/mid-gap ratio of PTIs is below 10% and hardly further improved duo to the lack of new bandwidth enhancement mechanism. In this paper, a PTI with the gap/mid-gap ratio of 16.25% is proposed. The designed PTI has a honeycomb lattice structure with triangular air holes, and such a wide bandwidth is obtained by optimizing the refractive-index profile of the primitive cell for increasing the energy proportion in the geometric perturbation region. The PTI shows a large topological nontrivial gap (the gap/mid-gap ratio 33.4%) with the bandwidth approaching its theoretical limit. The edge states propagate smoothly around sharp bends within 1430–1683 nm. Due to topological protection, the bandwidth only decreases 1.38% to 1450–1683 nm under 1%-random-bias disorders. The proposed PTI has a potential application in future high-capacity and nonlinear topological photonic devices.

【 授权许可】

CC BY