Abstract The recently emerging all-dielectric optical nanoantennas based on high-index semiconductors have proven to be an effective and low-loss alternative to metal-based plasmonic structures for light control and manipulations of light–matter interactions. Nonlinear optical effects have been widely investigated to employ the enhanced interactions between incident light and the dielectrics at the Mie-type resonances, and in particular magnetic dipole resonances, which are supported by the semiconductor. In this paper, we explore the novel phenomenon of bound states in the continuum supported by high-index semiconductor nanostructures. By carefully designing an array of nanodisk structures with an inner air slot as the defect, we show that a novel high quality-factor resonance achieved based on the concept of bound state in the continuum can be easily excited by the simplest linearly polarized plane wave at normal incidence. This resonance further enhances the interactions between light and semiconductors and boosts the nonlinear effects. Using AlGaAs as the nonlinear material, we demonstrate a significant increase in the second-harmonic generation efficiency, up to six orders of magnitude higher than that achieved by magnetic dipole resonances. In particular, a second-harmonic generation efficiency around 10% can be numerically achieved at a moderate incident pump intensity of 5 MW/cm2.

中文翻译：

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全介质天线阵列工作在连续介质的准束缚态并由线性极化平面波激发，显着增强了二次谐波的产生

摘要 最近出现的基于高指数半导体的全介电光学纳米天线已被证明是一种有效且低损耗的替代金属基等离子体结构的光控制和操纵光-物质相互作用的方法。非线性光学效应已被广泛研究，以在 Mie 型共振，特别是由半导体支持的磁偶极共振，利用入射光和电介质之间增强的相互作用。在本文中，我们探讨了由高指数半导体纳米结构支持的连续体中束缚态的新现象。通过精心设计以内部气隙为缺陷的纳米盘结构阵列，我们表明，基于连续介质中束缚态概念实现的新型高质量因子共振可以很容易地被最简单的垂直入射的线性偏振平面波激发。这种共振进一步增强了光与半导体之间的相互作用并增强了非线性效应。使用 AlGaAs 作为非线性材料，我们证明了二次谐波产生效率的显着提高，比磁偶极共振实现的效率高出六个数量级。特别是，在 5 MW/cm2 的中等入射泵浦强度下，可以在数值上实现约 10% 的二次谐波产生效率。这种共振进一步增强了光与半导体之间的相互作用并增强了非线性效应。使用 AlGaAs 作为非线性材料，我们证明了二次谐波产生效率的显着提高，比磁偶极共振实现的效率高六个数量级。特别是，在 5 MW/cm2 的中等入射泵浦强度下，可以在数值上实现约 10% 的二次谐波产生效率。这种共振进一步增强了光与半导体之间的相互作用并增强了非线性效应。使用 AlGaAs 作为非线性材料，我们证明了二次谐波产生效率的显着提高，比磁偶极共振实现的效率高出六个数量级。特别是，在 5 MW/cm2 的中等入射泵浦强度下，可以在数值上实现约 10% 的二次谐波产生效率。