论文标题
拓扑边缘模式从蜂窝光子晶体到三角晶格光子晶体的演变
Evolution of topological edge modes from honeycomb photonic crystals to triangular-lattice photonic crystals
论文作者
论文摘要
在两个扰动的蜂窝光子晶体的界面上存在拓扑边缘模式，通常归因于K和K $'$ valleys在K和K $'$ valleys处的浆果曲率的不同符号。与电子对应物相反，光子谷霍尔效应中定义的Chern数不是量化的数量，但可以通过更改几何扰动来调整为有限值，包括零。在这里，我们认为，即使浆果曲率消失，光子谷大厅效应中的边缘模式也可能存在。我们从数值上证明了三角形光子光子晶体板结构中零贝里曲面的边缘模式的存在，其中$ c_3 $对称性维持，但倒置对称性被损坏。我们研究了浆果曲率从蜂窝状光子光子晶体平板到三角形光子晶体板的演变，并表明三角形光子光子晶体仍然在非常宽的光子带盖中支持边缘模式。此外，我们发现零浆果曲率的边缘模式可以以极低的弯曲损失而传播。
The presence of topological edge modes at the interface of two perturbed honeycomb photonic crystals with $C_6$ symmetry is often attributed to the different signs of Berry curvature at the K and K$'$ valleys. In contrast to the electronic counterpart, the Chern number defined in photonic valley Hall effect is not a quantized quantity but can be tuned to finite values including zero simply by changing geometrical perturbations. Here, we argue that the edge modes in photonic valley Hall effect can exist even when Berry curvature vanishes. We numerically demonstrate the presence of the zero-Berry-curvature edge modes in triangular lattice photonic crystal slab structures in which $C_3$ symmetry is maintained but inversion symmetry is broken. We investigate the evolution of the Berry curvature from the honeycomb-lattice photonic crystal slab to the triangular-lattice photonic crystal slab and show that the triangular-lattice photonic crystals still support edge modes in a very wide photonic bandgap. Additionally, we find that the edge modes with zero Berry curvature can propagate with extremely low bending loss.
