Nichtlinieare plasmonische Nanoantennen aus Lithiumniobat

在第一个资助期内，成功探索了包括锂离子酸盐的纳米结构波导中的非线性过程，带来了一系列开创性的贡献。例子是新的相位匹配方案的建议，澄清的能力，以提高在金属波导中引导的表面等离子体激元极化激元的传播长度的参数放大，但也相邻的主题进行了探讨，如第一次观察到的艾里等离子体激元和光学纳米天线的线性特性的深入分析。在实验和理论的结合努力中进行的具有挑战性的工作有助于理解和控制光学纳米结构中光的超快非线性动力学。在第二个资助期内，以前开发的方法和手段将用于连贯地继续研究由嵌入纳米结构锂酸盐制成的非线性环境中的有限金属波导制成的腔体的超快非线性动力学。腔体基本上构成光学纳米天线，其中导模来回反弹并最终经历共振相互作用，其中遭受多次反射的等离子体激元相长干涉。这些谐振的存在理由由跨纳米天线传播的等离子体激元的相位累积和来自天线终端处的复反射系数的相位的贡献决定。这两个属性可以通过调整纳米天线和纳米天线终端的几何截面来随意调整非线性过程中所涉及的各种频率。这种组合提供了新的自由度，以实现迄今为止无法实现的有效非线性转换。此外，定制光学纳米天线的辐射图案的能力将在透视图中提供具有定向发射的集成非线性光源，并且通过同时叠加各种入射场，允许工程参数非线性过程远远超出现有技术。基于基本的理论理解和开发的实验技术，我们将针对该领域的主要挑战，例如通过非线性参数增益的等离子体共振的Q因子增强，通过自发下转换在纳米天线中产生纠缠光子，或用于高对比度传感器应用的纳米SHG光源。我们提出的工作是我们在前一个资助期内多种活动的延伸，并融合了优先计划的主要研究方向，即非线性，光学纳米天线，传播和相干控制。

The successful exploration of nonlinear processes in nanostructured waveguides comprising lithium niobate in the first funding period led to a series of groundbreaking contributions. Examples are suggestions for novel phase matching schemes, clarifications on the ability to enhance the propagation length of surface plasmon polaritons guided in metallic waveguides by parametric amplification, but also adjacent topics were explored such as the first observation of an Airy-plasmon and the in-depth analysis of linear properties of optical nanoantennas. The challenging work that has been performed in a combined experimental and theoretical effort served the purpose to understand and to control the ultrafast nonlinear dynamics of light in optical nanostructures. In the second funding period, the methodology and the means previously developed will be used to study in a coherent continuation the ultrafast nonlinear dynamics of cavities made from finite metallic nanowaveguides embedded into a nonlinear surrounding made of nanostructured lithium niobate. The cavities essentially constitute optical nanoantennas where a guided mode bounces back and forth and eventually experiencing a resonant interaction where the plasmons suffering from multiple reflections constructively interfere. The raison d'être of these resonances are dictated by the phase accumulation of the plasmons propagating across the nanoantenna and a contribution from the phase of the complex reflection coefficient at the antenna termination. Both properties can be adjusted at will for the various frequencies involved in the nonlinear process by tailoring the geometrical cross section of the nanoantennas and the nanoantenna termination. This combination provides novel degrees of freedoms to achieve efficient nonlinear conversion inaccessible thus far. Moreover, the ability to tailor the radiation pattern of the optical nanoantennas will provide in perspective an integrated nonlinear light-source with directed emission and allows engineering parametric nonlinear processes well beyond the current state of the art by superimposing simultaneously various incidence fields. Based on the fundamental theoretical understanding and the developed experimental techniques we will target major challenges of the field, as e.g. Q-factor enhancement of plasmonic resonances by nonlinear parametric gain, generation of entangled photons in nanoantennas by spontaneous downconversion, or nanosized SHG light sources for high contrast sensor applications. The work we propose is an extension of our manifold activities in the previous funding period and fuses the leitmotifs and the main research direction of the priority program, i.e. nonlinearity, optical nanoantennas, propagation, and coherent control.