发表机构
Shanghai Jiao Tong University; Shandong Normal University（上海交通大学; 山东师范大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究复折射率调制下光子时间晶体的拓扑性质，通过介电常数与电导率共同调制，发现Floquet谱整体移动及拓扑边缘态与动量带反转的关系，为时间域拓扑操控提供新途径。
AI 中文摘要
光子时间晶体通过对电磁参数进行时间上的周期调制而构建，具有独特的拓扑性质。在此，我们通过动态同时调节空间均匀材料的介电常数和电导率，探索了介电常数与电导率共同调制的PTC（PCM PTC），并发现了其独特的非厄米效应。我们发现，这种PCM PTC在虚准频率轴上具有Floquet谱的整体移动，该移动控制了动量带和带隙中的场放大与衰减。通过进一步考虑由两个不同PCM PTC组成的时间界面，我们分析了异常点处的本征态，从而揭示了拓扑边缘态的出现与动量带反转之间的关系。此外，PCM PTC的拓扑特征也可以从复Dirac质量中捕获。我们的工作研究了复调制机制下PTC的拓扑性质，为在时间域中操控拓扑边缘态提供了新的机会。
英文摘要
Photonic time crystals, constructed by periodic modulation of electromagnetic parameters in time, hold unique topological properties. Here, we explore permittivity and conductivity co-modulated PTCs (PCM PTCs) by dynamically tuning permittivity and conductivity simultaneously of the spatially-uniform materials, and discover their distinctive non-Hermitian effects. We find that such PCM PTCs hold a global shift of the Floquet spectrum along the imaginary quasifrequency axis, which controls field amplification and decay in both momentum bands and band gaps. By further considering the temporal interface consisting of two different PCM PTCs, we can unveil the relationship between the emergence of topological edge states and momentum band inversion by analyzing the eigenstates at exceptional points. Moreover, the characteristic of the topology of PCM PTCs can also be captured from the complex Dirac mass. Our work studies the topology of PTCs in complex modulation regime, offering new opportunities for manipulating topological edge states in the time domain.
