Broadband photonic topological insulator based on triangular-holes array with higher energy filling efficiency
Zhang Zhishen,
Li Feng,
Lu Jiuyang,
Liu Tao,
Heng Xiaobo,
He Yongcheng,
Liang Haohua,
Gan Jiulin,
Yang Zhongmin
Affiliations
Zhang Zhishen
School of Physics and Optoelectronic Technology, South China University of Technology, Guangzhou, Guangdong, 510640, China
Li Feng
School of Physics and Optoelectronic Technology, South China University of Technology, Guangzhou, Guangdong, 510640, China
Lu Jiuyang
School of Physics and Optoelectronic Technology, South China University of Technology, Guangzhou, Guangdong, 510640, China
Liu Tao
Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama, 351-0198, Japan
Heng Xiaobo
School of Physics and Optoelectronic Technology, South China University of Technology, Guangzhou, Guangdong, 510640, China
He Yongcheng
State Key Laboratory Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, 510640, China
Liang Haohua
State Key Laboratory Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, 510640, China
Gan Jiulin
State Key Laboratory Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, 510640, China
Yang Zhongmin
School of Physics and Optoelectronic Technology, South China University of Technology, Guangzhou, Guangdong, 510640, China
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.
