arXiv 2202.030732022-02physics.opticscond-mat.mtrl-sci

全介质超颖表面中连续介质中偶然双束缚态的剪裁

Tailoring accidental double bound states in the continuum in all-dielectric metasurfaces

Diego R. Abujetas, Jorge Olmos-Trigo, José A. Sánchez-Gil

备注：: 18 pages, 7 figures

摘要：

连续介质中的束缚态（BIC）由于其形式上发散的Q因子，特别是在$Γ$点（平面内波矢$k_{||}=0$）对称保护的全介电纳米结构超颖表面中出现的那些束缚态，已经被彻底研究。较少注意可能出现在支持模式的能带结构中的任何其他$k_{||}\not =0$处的偶然BIC，其反过来难以预测。在这里，我们利用耦合的电/磁偶极子模型，以确定分析条件的出现意外BIC，有效的任何平面阵列的元原子，可以描述的偶极共振，这是许多纳米结构的情况下，在光学领域。这是探索全介电纳米球通过明确的分析条件，使我们反过来预测意外BIC的位置在参数空间$(ω,\bf{k_{||}}$）。最后，利用这些条件来确定不仅单，而且双（两个线性极化）意外BIC发生在相同的位置在色散关系$ω-\bf{k_{||}}$为现实的半导体纳米盘元原子。这可能为纳米尺度下的各种BIC增强的光-物质相互作用现象铺平道路，例如激光或非线性转换，这些现象受益于远离$Γ$点（偏离法向入射）的波矢量，重叠两个线性偏振。

英文摘要：

Bound states in the continuum (BICs) have been thoroughly investigated due to their formally divergent Q-factor, especially those emerging in all-dielectric, nanostructured metasurfaces from symmetry protection at the $Γ$ point (in-plane wavevector $k_{||}=0$). Less attention has been paid to accidental BICs that may appear at any other $k_{||}\not =0$ in the band structure of supported modes, being in turn difficult to predict. Here we make use of a coupled electric/magnetic dipole model to determine analytical conditions for the emergence of accidental BICs, valid for any planar array of meta-atoms that can be described by dipolar resonances, which is the case of many nanostructures in the optical domain. This is explored for all-dielectric nanospheres through explicit analytical conditions that allow us in turn to predict accidental BIC positions in the parameter space $(ω,\bf{k_{||}}$). Finally, such conditions are exploited to determine not only single, but also double (for both linear polarizations) accidental BICs occurring at the same position in the dispersion relation $ω-\bf{k_{||}}$ for realistic semiconductor nanodisk meta-atoms. This might pave the way to a variety of BIC-enhanced light-matter interaction phenomena at the nanoscale such as lasing or non-linear conversion, that benefit from emerging at wavevectors away from the $Γ$ point (off-normal incidence) overlapping for both linear polarizations.

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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