论文标题
通过在金属表面上通过电子溢出来增强第二次谐波产生
Enhancing second-harmonic generation with electron spill-out at metallic surfaces
论文作者
论文摘要
二阶非线性光学过程并未在大部分的中心对称材料中表现出来，但可能发生在表面的Angstroms-Thick层中。在这样的长度尺度上，量子机械效应发挥了作用，这对于血浆系统的准确描述至关重要。在本文中，我们开发了一个基于量子水动力学描述的理论模型，以研究等离子系统中的自由电子非线性动力学。我们的模型预测了金属表面上电子密度溢出引起的强共振。我们表明，这些共振可以提高第二次谐波生成效率高达四个数量级，并且可以通过沿薄介电层来控制金属表面的电子溢出来任意调整。这些结果提供了通过在量子水平上进行工程光学特性来人为地增加非线性敏感性的可能性。
Second-order nonlinear optical processes do not manifest in the bulk of centrosymmetric materials, but may occur in the angstroms-thick layer at surfaces. At such length-scales, quantum mechanical effects come into play which could be crucial for an accurate description of plasmonic systems. In this article, we develop a theoretical model based on the quantum hydrodynamic description to study free-electron nonlinear dynamics in plasmonic systems. Our model predicts strong resonances induced by the spill-out of electron density at the metal surface. We show that these resonances can boost second-harmonic generation efficiency up to four orders of magnitude and can be arbitrarily tuned by controlling the electron spill-out at the metal surface with the aid of thin dielectric layers. These results offer a possibility to artificially increase nonlinear susceptibilities by engineering optical properties at the quantum level.
