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arXiv 2209.09644physics.optics
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连续统中的拓扑Floquet束缚态

Topological Floquet bound states in the continuum

Chunyan Li, Yaroslav V. Kartashov, Vladimir V. Konotop

摘要:

具有锯齿形边缘和与边缘正交的折射率梯度的螺旋波导的蜂窝阵列可以支持连续体中的Floquet束缚态(BIC)。折射率的梯度导致Floquet-Bloch光谱的强不对称性。创建这种Floquet BIC的机制被理解为出现交叉和避免由空间有限的条带阵列支持的分支的交叉。有限阵列的整个频谱被分裂成体分支的边缘状态在扩展区的延续,揭示多个自交叉和体模式断开的间隙状态,避免交叉。由于梯度的存在,系统中几乎所有的态都是局域化的,但拓扑边缘态比其他态表现出更强的局域化。这种强局域化的Floquet BIC与局域化的Wannier-Stark样体模共存。边缘Floquet状态的鲁棒性被确认通过一个本地化的边缘缺陷的形式,一个失踪的波导。

英文摘要:

A honeycomb array of helical waveguides with zigzag-zigzag edges and a refractive index gradient orthogonal to the edges may support Floquet bound states in continuum (BICs). The gradient of the refractive index leads to strong asymmetry of the Floquet-Bloch spectrum. The mechanism of creation of such Floquet BICs is understood as emergence of crossings and avoided crossings of the branches supported by spatially limited stripe array. The whole spectrum of a finite array is split into the bulk branches being continuation of the edge states in the extended zone revealing multiple self-crossings and bulk modes disconnected from the gap states by avoided crossing. Nearly all states in the system are localized due to the gradient, but topological edge states manifest much stronger localization than other states. Such strongly localized Floquet BICs coexist with localized Wannier-Stark-like bulk modes. Robustness of the edge Floquet states is confirmed by their passage through a localized edge defect in the form of a missing waveguide.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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