论文标题
在层堆积的介电光子晶体中的淋巴结线的隐藏对称性固定点
Hidden-symmetry-enforced nexus points of nodal lines in layer-stacked dielectric photonic crystals
论文作者
论文摘要
最近证明，从介电光子晶体中从零频率中出现的频段的连接性与其具有相同空间组的电子对应物不同。我们发现，在由各向异性电介质组成的AB层堆叠的光子晶体中，独特的光子带连接性在两个节点环和Kramers样节点线的Nexuses处带来了一种新型的对称对称性的Triply Demanter点。线节点的出现和交点是通过麦克斯韦方程的一般1/4-周期螺钉旋转对称性来保证的。在Nexus Point附近的$ K_Z $和ISO频率表面的频段均以Spin-1类似于dirac的锥体分散，从而产生了Nexus Point的光的异国传输特征。我们表明，自旋-1锥形衍射发生在Nexus点，可用于操纵光学涡旋的电荷。我们的工作表明，麦克斯韦的方程可能会由材料张量组件的分数周期性引起的隐藏对称性，因此为寻找新型的拓扑结节结构铺平了方式。
It was recently demonstrated that the connectivities of bands emerging from zero frequency in dielectric photonic crystals are distinct from their electronic counterparts with the same space groups. We discover that, in an AB-layer-stacked photonic crystal composed of anisotropic dielectrics, the unique photonic band connectivity leads to a new kind of symmetry-enforced triply degenerate points at the nexuses of two nodal rings and a Kramers-like nodal line. The emergence and intersection of the line nodes are guaranteed by a generalized 1/4-period screw rotation symmetry of Maxwell's equations. The bands with a constant $k_z$ and iso-frequency surfaces near a nexus point both disperse as a spin-1 Dirac-like cone, giving rise to exotic transport features of light at the nexus point. We show that the spin-1 conical diffraction occurs at the nexus point which can be used to manipulate the charges of optical vortices. Our work reveals that Maxwell's equations can have hidden symmetries induced by the fractional periodicity of the material tensor components and hence paves the way to finding novel topological nodal structures unique to photonic systems.
