Chen Jianfeng, Qin Qiumeng, Peng Chaoqun, Li Zhi-Yuan
Opt Express. 2022 Jun 6;30(12):21621-21633. doi: 10.1364/OE.457593.
Recent developments in topological photonics have shown that the introduction of disorders can yield the innovative and striking transport phenomena. Here, we theoretically investigate topological one-way edge states in radius-fluctuated photonic Chern topological insulators (PCTIs), which are composed of two-dimensional gyromagnetic photonic crystals with cylinder site fixed but with cylinder radius fluctuated. We use a fluctuation index to characterize the degree of radius fluctuation, employ two empirical parameters to inspect the evolution of topological one-way edge states, and verify the stability of topological one-way edge states by calculating massive samples with various random numbers. We find that as the radius-fluctuation strength increases, there arises a competition between topological one-way edge state, Anderson localization state and trivial bulk state. We reveal that the Anderson localization state appears far more easily in the radius-fluctuation PCTI with even a weak strength compared with the position-perturbed PCTI with a strong randomness. We also demonstrate that the topological one-way edge states are protected against a strong fluctuation much larger than the fabrication errors in practical experiments. Our results show that the PCTIs consisting of gyromagnetic photonic crystals have a high-tolerance for the material and sample fabrication errors, and this would provide a deeper understanding of fundamental topology physics.
拓扑光子学的最新进展表明，引入无序可以产生创新且引人注目的输运现象。在此，我们从理论上研究了半径波动的光子陈拓扑绝缘体（PCTIs）中的拓扑单向边缘态，该绝缘体由二维旋磁光子晶体组成，其圆柱位置固定但半径波动。我们用一个波动指数来表征半径波动的程度，采用两个经验参数来考察拓扑单向边缘态的演化，并通过计算具有各种随机数的大量样本验证拓扑单向边缘态的稳定性。我们发现，随着半径波动强度的增加，拓扑单向边缘态、安德森局域态和平凡体态之间出现了竞争。我们揭示，与具有强随机性的位置微扰PCTI相比，即使在强度较弱的半径波动PCTI中，安德森局域态也更容易出现。我们还证明，拓扑单向边缘态能够抵御比实际实验中的制造误差大得多的强波动。我们的结果表明，由旋磁光子晶体组成的PCTIs对材料和样本制造误差具有高耐受性，这将为基础拓扑物理学提供更深入的理解。
