High field terahertz plasmonics

目的本研究项目的目的是展示利用具有极高峰值电场的太赫兹脉冲进行传感和非线性光谱学的新技术。我们的方法是将我们最近在等离子体诱导场增强方面的工作与新开发的高能太赫兹脉冲产生技术结合起来。亚波长金属结构附近的等离子体相互作用产生了微小的电磁能量密度增强区域。当这些结构被高能超短脉冲激发时，产生的场强将是巨大的，完全进入非线性光学的范围。这两种思想的结合，对太赫兹辐射进行了优化，将开辟一个太赫兹非线性光学的新领域。这个研究项目的智力价值在于开发了基于强太赫兹场引起的非线性相互作用的时间分辨光谱研究的灵敏新技术。此外，利用太赫兹非线性光学效应检测极少量分析物的能力，具有高时间和空间分辨率，将揭示以前受样本量和非均匀性限制所掩盖的新的动态过程。最后，这项工作将使非线性表面等离子体传播的研究成为可能，并将有助于我们理解从太赫兹到光学频率的高场等离子体动力学。更广泛的影响通过产生迄今为止报道的最高太赫兹场并研究它们与材料的相互作用，这项工作将建立利用高阶非线性相互作用的可能性。它还将展示具有重大技术意义的太赫兹传感新技术。更广泛地说，这项研究将通过建立一个高场太赫兹光-物质相互作用的新学科，改变我们对太赫兹体制中科学极限的看法。

ObjectiveThe aim of this research program is to demonstrate new techniques for sensing and nonlinear spectroscopy using terahertz pulses with very high peak electric fields. Our approach is to combine our recent work on plasmon-induced field enhancements with newly developed techniques for high-energy terahertz pulse generation. Plasmonic interactions near subwavelength metal structures give rise to tiny regions of enhanced electromagnetic energy density. When these structures are excited by high-energy ultrashort pulses, the resulting field strengths will be huge, well into the regime of nonlinear optics. The combination of these two ideas, optimized for terahertz radiation, will open up a new realm of terahertz nonlinear optics.Intellectual MeritThe intellectual merit of this research program lies in the development of sensitive new techniques for time-resolved spectroscopic studies based on nonlinear interactions induced by strong terahertz fields. In addition, the ability to detect very small quantities of an analyte using terahertz nonlinear optical effects, with high temporal and spatial resolution, will reveal new dynamical processes previously obscured by limitations of sample size and inhomogeneity. Finally, this work will enable the study of nonlinear surface plasmon propagation, and will contribute to our understanding of high-field plasmon dynamics from terahertz to optical frequencies.Broader ImpactsBy generating the highest terahertz fields yet reported and studying their interaction with materials, this work will establish the possibility of exploiting higher-order nonlinear interactions. It will also demonstrate new techniques for terahertz-based sensing, which are of great technological importance. More broadly, this research will change our view of the limits of science in the THz regime by establishing a new discipline of high-field terahertz light-matter interactions.