Abstract 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.

中文翻译：

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具有更高能量填充效率的基于三角孔阵列的宽带光子拓扑绝缘体

摘要 由于宽带拓扑保护，光子拓扑绝缘体（PTI）为具有低耗散和信号在宽波长范围内定向传输的光子器件带来了显着的新机遇。然而，由于缺乏新的带宽增强机制，PTI 的最大间隙/中间隙比低于 10%，并且很难进一步改善。在本文中，提出了间隙/中间间隙比为 16.25% 的 PTI。设计的 PTI 具有带有三角形气孔的蜂窝晶格结构，如此宽的带宽是通过优化原始单元的折射率分布以增加几何扰动区域的能量比例来获得的。PTI 显示了一个大的拓扑非平凡间隙（间隙/中间间隙比为 33.4%），带宽接近其理论极限。边缘状态在 1430-1683 nm 内的锐弯附近平滑传播。由于拓扑保护，带宽在 1% 随机偏置障碍下仅减少 1.38% 至 1450-1683 nm。所提出的 PTI 在未来的高容量和非线性拓扑光子器件中具有潜在的应用。