Nonlinear harmonic generation in metasurfaces has shown great promise for applications such as novel light sources, nonlinear holography, and nonlinear imaging. In particular, dielectric metasurfaces have shown multifold enhancement of the harmonic efficiency in comparison to their plasmonic counterparts due to lower optical loss and much higher damage threshold. In this work, we propose to enhance the efficiency of the third harmonic generation in a complementary silicon nonlinear metasurface, consisting of nanoapertures of cross-like shape in the silicon film. The efficiency enhancement is based on a multipolar interference between the magnetic dipole and electric quadrupole, resulting in significant near-field enhancement and a large mode volume of the nonlinear interaction. The measured efficiency of third harmonic generation from the silicon metasurface is 100× higher than that from a planar silicon film of the same thickness. Numerical analysis of the near-field resonant modes confirms the multipolar mechanism of nonlinear enhancement. Enhanced third harmonic generation by multipolar interference in complementary dielectric nanostructure opens a new route for developing high-efficiency nonlinear metasurfaces.

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互补硅超表面中的多极干扰增强了三次谐波的产生

超颖表面中的非线性谐波产生对于新型光源，非线性全息术和非线性成像等应用已显示出巨大的希望。特别地，由于较低的光损耗和高得多的损伤阈值，介电超表面与等离子激元相比显示出谐波效率的多重提高。在这项工作中，我们建议提高互补硅非线性超表面中三次谐波的产生效率，该互补非线性硅表面由硅膜中类似十字形的纳米孔组成。效率增强是基于磁偶极子和电四极子之间的多极干扰，从而导致近场增强和非线性相互作用的较大模式体积。与相同厚度的平面硅膜相比，从硅超表面产生的三次谐波的测量效率要高100倍。近场共振模态的数值分析证实了非线性增强的多极机制。互补介电纳米结构中多极性干扰增强了三次谐波的产生，为开发高效的非线性超颖表面开辟了一条新途径。