Breakdown effect of periodic perturbations to the robustness of topological phase in a gyromagnetic photonic crystal

作者：Tian, Y.; Zhou, Rui; Liu, Zheng-Rong; Liu, Y.^*; Lin, Hai^*; Zhou, Bin

来源：IET Optoelectronics, 2023, 17(6): 249-256.

DOI：10.1049/ote2.12106

• photonic crystals
• topological insulators

In the known field of topological photonics, what remains less so is the breakdown effect of topological phases deteriorated by perturbation. In this study, the authors investigate the variance on topological invariants for a periodic Kekule medium perturbed in unit cells, which was a gyromagnetic photonic crystal holding topological phases induced by synchronised rotation of unit cells. Two parameters for geometric and material perturbation are respectively benchmarked to characterise the topological degradation. Our calculation demonstrates that such a periodic perturbation easily destructs the topological phase and thus calls for further checkups on robustness under such unit-cell-perturbation in realisation. @@@ In our paper, the authors take the simple case of periodic randomisation by disrupting two parameters in unit cells. The authors characterise the topological breakdown via directly calculating variances to Chern numbers under their defined perturbation. Their calculation demonstrates that such a periodic perturbation easily annihilates topological invariants, providing benchmark for future design of these topological devices.image

• 单位
  兰州大学; y