Lifting the nodal ring degeneracy can result in topologically nontrivial ridge bulk states and associated interface states, which have been realized by 1D photonic crystals. However, the ridge interface states exist only for p polarization, which limits their potential applications in polarization-independent optical devices. Here, a scheme to design the polarization-independent nodal ring using a 1D photonic crystal is proposed. It is revealed that the fourfold degeneracy exactly lies at the position where the absentee layer condition is satisfied for each layer. Once the absentee layer condition cannot be satisfied for each layer, the nodal ring will be gapped, accompanied by ridge interface states traversing the gap. Interestingly, these p-polarized and s-polarized ridge interface states are degenerate almost in the whole band gap, which facilitates polarization-independent optical filtering. This work proposes a novel way for polarization-independent optical filtering and associated applications, such as high-efficiency solar energy conversion and privacy screen.

中文翻译：

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脊光子晶体中的双偏振拓扑界面态


提高节环简并性可以产生拓扑上非平凡的脊体态和相关的界面态，这已通过一维光子晶体实现。然而，脊界面态仅存在于p偏振，这限制了它们在偏振无关光学器件中的潜在应用。这里，提出了一种使用一维光子晶体设计偏振无关节点环的方案。结果表明，四重简并性恰好位于各层满足缺席层条件的位置。一旦每层都不能满足缺席层条件，节环将出现间隙，并伴随着穿过间隙的脊界面态。有趣的是，这些p偏振和s偏振脊界面态几乎在整个带隙中简并，这有利于偏振无关的光学滤波。这项工作提出了一种与偏振无关的光学滤波和相关应用的新方法，例如高效太阳能转换和隐私屏幕。