连续介质中束缚态辅助的多带全介质超表面中的增强三次谐波产生
Enhanced Third-Harmonic Generation in a Bound State in the Continuum Assisted Multiband All-Dielectric Metasurface
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- King Abdullah University of Science and Technology (KAUST)（阿卜杜拉国王科技大学）
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中文总结 AI 辅助
该研究设计了含硅纳米块的全介质超表面，利用连续介质中的准束缚态实现多带Fano共振，增强了紫外多带三次谐波产生，为多带光子器件研发提供了新途径。
中文摘要 AI 辅助
在近红外波段，研究人员展示了多带Fano共振，其采用的全介质超表面单元结构为玻璃基底上的四个硅纳米块。面内不对称性触发了对称性保护的连续介质中的准束缚态（QBICs），产生多个高品质因子共振。通过对散射截面和共振处的场分布进行多极分解，确定了这些共振的起源。这些共振处的强场局域化可实现紫外波段高效的多带三次谐波（TH）产生，在峰值泵浦强度为$1.6\\,\mathrm{GW/cm^{2}}$时，模拟得到的最大转换效率为$8.5 \times 10^{-3}$。研究人员制备了对称和非对称两种构型的超表面，并在正入射条件下测量了其线性和非线性响应，在峰值泵浦强度为$3.25\\,\mathrm{GW/cm^{2}}$时，获得的TH转换效率为$1.2 \times 10^{-6}$。这些结果为多带光子器件提供了可行路径，包括多波长激光器、多带谐波产生以及量子光子学用单光子源。
英文摘要
Multiband Fano resonances are demonstrated in the near-infrared (near-IR) using an all-dielectric metasurface whose unit cell consists of four silicon nanoblocks on a glass substrate. An in-plane asymmetry triggers symmetry-protected quasi-bound states in the continuum (QBICs), producing multiple high-Q resonances. Their origin is identified through multipolar decomposition of the scattering cross section and field distributions at the resonances. The strong field localization at these resonances enables efficient multiband third-harmonic (TH) generation in the ultraviolet (UV), with a maximum simulated conversion efficiency of $8.5 \times 10^{-3}$ at a peak pump intensity of $1.6\,\mathrm{GW/cm^{2}}$. The metasurface is fabricated in symmetric and asymmetric configurations, and its linear and nonlinear responses are measured under normal incidence. A TH conversion efficiency of $1.2 \times 10^{-6}$ is obtained at a peak pump intensity of $3.25\,\mathrm{GW/cm^{2}}$. These results establish a route to multiband photonic devices, including multiwavelength lasers, multiband harmonic generation, and single-photon sources for quantum photonics.
