Zhuang Suna, Chen Jianfeng, Liang Wenyao, Li Zhi-Yuan
Opt Express. 2021 Jan 18;29(2):2478-2487. doi: 10.1364/OE.412460.
We have studied the coupling effect of topological photonic states in a double-channel magneto-optical photonic crystal waveguide by introducing a two-stranded ordinary AlO photonic crystal as the coupling layer. There exist both M1 (odd) and M2 (even) one-way modes simultaneously in the bandgap. Interestingly, M1 mode is always a fast-light mode with large group velocity (vg) and large group velocity dispersion (GVD) regardless what the radius (RA) of AlO rods is. However, when RA is appropriate, M2 mode becomes a very slow-light mode exhibiting near-zero vg and zero GVD simultaneously. The physical reason of such slow-light is attributed to the strong coupling effect between the one-way edge modes in both sub-waveguides. Furthermore, the simulation results show that the robustness of both the fast- and slow-light modes are extremely strong against perfect electric conductor defect and the one-way transmittance is close to 100%. Besides, the PEC defect can cause significant phase delay. These results hold promise for many fields such as signal processing, optical modulation, and the design of various topological devices.
我们通过引入双链普通AlO光子晶体作为耦合层，研究了双通道磁光光子晶体波导中拓扑光子态的耦合效应。在带隙中同时存在M1（奇数）和M2（偶数）单向模式。有趣的是，无论AlO棒的半径（RA）是多少，M1模式始终是具有大群速度（vg）和大群速度色散（GVD）的快光模式。然而，当RA适当时，M2模式会变成一种非常慢的光模式，同时呈现出接近零的vg和零GVD。这种慢光的物理原因归因于两个子波导中单向边缘模式之间的强耦合效应。此外，模拟结果表明，快光和慢光模式对理想导体缺陷的鲁棒性都极强，单向透过率接近100%。此外，PEC缺陷会导致显著的相位延迟。这些结果在信号处理、光调制以及各种拓扑器件的设计等许多领域都有应用前景。
