Opt Express. 2023 Jun 19;31(13):21626-21640. doi: 10.1364/OE.485765.
In this work, a theorem is proved stating that in various types of waveguides with mirror reflection symmetries, the electromagnetic duality correspondence between eigenmodes of complementary structures induces counterpropagating spin-polarized states. The mirror reflection symmetries may be preserved around one or more arbitrary planes. Pseudospin-polarized waveguides supporting one-way states manifest robustness. This is similar to topologically non-trivial direction-dependent states guided by photonic topological insulators. Nevertheless, a remarkable aspect of our structures is that they can be implemented in extremely broad bandwidth by simply using complementary structures. Based on our theory, the concept of the pseudospin polarized waveguide can be realized using dual impedance surfaces ranging from microwave to optical regime. Consequently, there is no need to employ bulk electromagnetic materials to suppress backscattering in waveguiding structures. This also includes pseudospin-polarized waveguides with perfect electric conductor-perfect magnetic conductor boundaries where the boundary conditions limit the bandwidth of waveguides. We design and develop various unidirectional systems and the spin-filtered feature in the microwave regime is further investigated.
在这项工作中，证明了一个定理，即在具有镜像反射对称性的各种类型的波导中，互补结构的本征模式之间的电磁对偶对应关系诱导了反向传播的自旋极化态。镜像反射对称性可以在一个或多个任意平面周围保持。支持单向态的赝自旋极化波导表现出稳健性。这类似于由光子拓扑绝缘体引导的具有拓扑非平凡方向依赖性的状态。然而，我们结构的一个显著特点是，它们可以通过简单地使用互补结构在非常宽的带宽内实现。基于我们的理论，使用从微波到光学范围的双阻抗表面可以实现赝自旋极化波导的概念。因此，不需要使用体电磁材料来抑制波导结构中的反向散射。这也包括具有完美电导体-完美磁导体边界的赝自旋极化波导，其中边界条件限制了波导的带宽。我们设计和开发了各种单向系统，并进一步研究了微波频段的自旋滤波特性。
