Nussbaum Eric, Sauer Erik, Hughes Stephen
Opt Lett. 2021 Apr 1;46(7):1732-1735. doi: 10.1364/OL.420080.
Topological photonic crystal waveguides can create edge states that may be more robust against fabrication disorder and can yield propagation modes below the light line. We present a fully three-dimensional method to modify state-of-the-art designs to achieve a significant bandwidth improvement for lossless propagation. Starting from an initial design with a normalized bandwidth of 7.5% (13.4 THz), the modification gives more than 100% bandwidth improvement to 16.2% (28.0 THz). This new design is obtained using an automatic differentiation enabled inverse design and a guided mode expansion technique to efficiently calculate the band structure and edge state modes.
拓扑光子晶体波导可以产生边缘态，这些边缘态可能对制造无序更具鲁棒性，并且可以产生低于光线的传播模式。我们提出了一种全三维方法来修改现有设计，以实现无损传播的显著带宽提升。从归一化带宽为7.5%（13.4太赫兹）的初始设计开始，修改后的带宽提升超过100%，达到16.2%（28.0太赫兹）。这种新设计是通过使用支持自动微分的逆设计和导模展开技术来有效计算能带结构和边缘态模式而获得的。
