论文标题
小型体积拓扑光子光子状态在一维晶格中与偶极子 - Quadrupole相互作用
Small mode volume topological photonic states in one-dimensional lattices with dipole--quadrupole interactions
论文作者
论文摘要
我们在偶极子近似之外的一维（1-D）晶格中研究了拓扑光子状态。通过偶联偶极子 - Quadrupole方法分析研究了血浆纳米颗粒之间近场相互作用支持的晶格的电磁共振。两分晶格中的拓扑相变是由Zak相的变化确定的。我们的结果揭示了四极力矩对近场相互作用和乐队拓扑的贡献。发现非平凡晶格中的拓扑边缘状态具有偶极性和四极性性质。四极边缘状态不仅是偶极边缘状态的正交，而且在不同的sublattices上也位于空间上。此外，在相同能量与四极平面谱带的相同能量共存的四极拓扑边缘状态具有较短的定位长度，因此比传统的偶极边缘状态更小。这些发现加深了我们在涉及高阶多物体的拓扑系统中的理解，或类似于具有较高角度动量的量子系统中的波函数，并且可能有助于设计拓扑系统，以限制稳健的光线并增强轻度互动。
We study the topological photonic states in one-dimensional (1-D) lattices analogue to the Su-Schrieffer-Heeger (SSH) model beyond the dipole approximation. The electromagnetic resonances of the lattices supported by near-field interactions between the plasmonic nanoparticles are studied analytically with coupled dipole--quadrupole method. The topological phase transition in the bipartite lattices is determined by the change of Zak phase. Our results reveal the contribution of quadrupole moments to the near-field interactions and the band topology. It is found that the topological edge states in non-trivial lattices have both dipolar and quadrupolar nature. The quadrupolar edge states are not only orthogonal to the dipolar edge states, but also spatially localized at different sublattices. Furthermore, the quadrupolar topological edge states, which coexist at the same energy with the quadrupolar flat band have shorter localization length and hence smaller mode volume than the conventional dipolar edge states. The findings deepen our understanding in topological systems that involve higher-order multipoles, or in analogy to the wave functions in quantum systems with higher-orbital angular momentum, and may be useful in designing topological systems for confining light robustly and enhancing light-matter interactions.
