Photonic crystal (PhC) consisting of a square lattice of ferrite rods with remanence in the air is theoretically investigated. It is shown that such a PhC can possess a large band gap with a nontrivial topological property. By interfacing the PhC with different cladding materials, which have (bulk-mode) band gaps with different topological properties, different types of one-way modes that are immune to backscattering are achieved in the absence of an external magnetic field. It is numerically demonstrated that by using such one-way modes, waves can be flexibly and effectively manipulated in PhC systems without almost any power loss.

中文翻译：

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没有外部磁场的光子晶体中的鲁棒单向模式

理论上研究了由具有空气中剩磁的铁氧体棒的方形晶格组成的光子晶体 (PhC)。结果表明，这种 PhC 可以具有大的带隙和非平凡的拓扑特性。通过将 PhC 与具有不同拓扑特性的（体模式）带隙的不同包层材料连接起来，可以在没有外部磁场的情况下实现不同类型的不受反向散射影响的单向模式。数值证明，通过使用这种单向模式，可以在 PhC 系统中灵活有效地操纵波，而几乎没有任何功率损耗。