Meta-devices have significantly revitalized the study of nonlinear optical phenomena. At the nanoscale, the detrimental effects of phase mismatching between fundamental and harmonic waves can be substantially reduced. This review analyzes the theoretical frameworks of how plasmonic and dielectric materials induce nonlinear optical properties. Plasmonic and dielectric nonlinear meta-devices that can excite strong resonant modes for efficiency enhancement are explored. We outline different strategies designed to shape the radiation pattern in order to increase the collection capability of nonlinear signals emitted from meta-devices. In addition, we discuss how nonlinear phase manipulation in meta-devices can integrate the benefits of efficiency enhancement and radiation shaping, not only boosting the energy density of the nonlinear signal but also facilitating a wide range of applications. Finally, potential research directions within this field are discussed.

中文翻译：

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非线性超元器件：从等离子体到电介质


超设备极大地振兴了非线性光学现象的研究。在纳米尺度上，基波和谐波之间相位失配的不利影响可以大大降低。本文分析了等离子体和介电材料如何诱导非线性光学特性的理论框架。本文探讨了可以激发强谐振模式以提高效率的等离子体和介电非线性超元器件。我们概述了旨在塑造辐射方向图的不同策略，以提高从元器件发射的非线性信号的收集能力。此外，我们还讨论了超器件中的非线性相位操纵如何整合效率增强和辐射整形的优势，不仅可以提高非线性信号的能量密度，还可以促进广泛的应用。最后，讨论了该领域内的潜在研究方向。