Terahertz Plasmonics for Linear and Nonlinear Spectroscopy and Sensing

用于线性和非线性光谱和传感的太赫兹等离子体

• 批准号: 1505536
• 负责人: Daniel Mittleman
• 金额: $ 40万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1505536&HistoricalAwards=false
• 关键词: Terahertz; Plasmonics; Linear; Nonlinear; Spectroscopy

Terahertz science and technology has become one of the most exciting research frontiers in recent years. This long-neglected portion of the electromagnetic spectrum (with frequencies ranging from about 0.1 to 5 THz, which corresponds to wavelengths from about 0.06 to 3 mm) has attracted a great deal of attention, because of the many possible research and technology applications. One important area is terahertz sensing, which exploits the unique spectroscopic signatures of materials for detection and identification. Recent research has shown that the terahertz range is spectroscopically rich, with many different substances possessing strong and unique absorption fingerprints. Sensitive sensing technologies would therefore have wide-ranging applications, in areas as diverse as food monitoring and chemical weapons detection. However, the field has been hampered by the relatively poor sensitivity of terahertz systems. By contrast, state-of-the-art mid-infrared absorption spectroscopy achieves parts-per-trillion detection levels, and surface-enhanced Raman scattering in the visible or near- infrared can be used to detect the spectroscopic signature of a single molecule. The aim of this research program is to demonstrate new techniques for sensing and spectroscopy using terahertz pulses, including pulses with very high peak electric fields. The approach is to build on recent work which explored the giant enhancements of fields that can occur in the local environment of small metallic structures. These ideas will be combined with newly developed techniques for high-energy terahertz pulse generation. This combination will enable the generation of extremely high local field strengths, opening up a new realm for extreme light-matter interactions in the terahertz range, and pointing the way towards vast improvements in the sensitivity of terahertz sensing systems.This comprehensive three-year research program has several important goals. It will pioneer the development of sensitive new techniques for time-resolved spectroscopic studies based on nonlinear interactions induced by strong terahertz fields. By 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 such as Raman scattering, which have been essentially absent from the THz literature. It will also demonstrate new techniques for sensing based on these nonlinear interactions, which are of great technological importance. The scope of the project is defined by two broad research thrusts. The first will investigate the new possibilities enabled by plasmonic devices for sensing and manipulation of terahertz waves. This will include the study of metasurfaces, including those fabricated on active substrates which can be switched electrically. It will also involve the use of atomic force microscopy for tip-enhanced near-field spectroscopies including near-field emission spectroscopy. The second thrust will explore the possibilities offered by nonlinear interactions induced by these plasmonic local field enhancements, by integrating these plasmonic devices together with high-intensity terahertz incident fields. Broadly speaking, this work will change the prevailing view of terahertz science, which is generally thought to be confined to the low- field or perturbative limit. By extending the recent breakthrough work on terahertz high-field generation, this project will establish a new discipline of extreme terahertz light-matter interactions.

太赫兹科学技术是近年来最令人兴奋的研究前沿之一。 由于许多可能的研究和技术应用，电磁波谱的这一长期被忽视的部分（频率范围为约0.1至5 THz，对应于约0.06至3 mm的波长）吸引了大量关注。 一个重要的领域是太赫兹传感，它利用材料的独特光谱特征进行检测和识别。 最近的研究表明，太赫兹范围是光谱丰富的，许多不同的物质具有强烈和独特的吸收指纹。 因此，敏感传感技术将在食品监测和化学武器探测等不同领域有着广泛的应用。 然而，太赫兹系统相对较差的灵敏度阻碍了该领域的发展。 相比之下，现有技术的中红外吸收光谱法实现万亿分之几的检测水平，并且可见光或近红外中的表面增强拉曼散射可用于检测单个分子的光谱特征。这项研究计划的目的是展示使用太赫兹脉冲的传感和光谱学新技术，包括具有非常高峰电场的脉冲。 该方法是建立在最近的工作，探索了巨大的增强场，可以发生在局部环境中的小金属结构。 这些想法将与新开发的高能太赫兹脉冲产生技术相结合。 这种结合将能够产生极高的局部场强，为太赫兹范围内的极端光-物质相互作用开辟了一个新的领域，并为太赫兹传感系统的灵敏度的巨大改进指明了方向。 它将开创基于强太赫兹场诱导的非线性相互作用的时间分辨光谱研究的敏感新技术的发展。通过产生最高的太赫兹领域尚未报道，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，如拉曼散射，这基本上是缺乏太赫兹文献的可能性。 它还将展示基于这些非线性相互作用的传感新技术，这些技术具有重要的技术意义。 该项目的范围由两个广泛的研究重点确定。第一个将研究等离子体激元器件用于太赫兹波的传感和操纵的新可能性。 这将包括对超颖表面的研究，包括那些在有源衬底上制造的可以电开关的超颖表面。 它还将涉及使用原子力显微镜的尖端增强近场光谱，包括近场发射光谱。 第二个推力将探索由这些等离子体局部场增强引起的非线性相互作用提供的可能性，通过将这些等离子体器件与高强度太赫兹入射场集成在一起。 从广义上讲，这项工作将改变目前对太赫兹科学的普遍看法，这种看法通常被认为局限于低场或微扰极限。 通过扩展最近在太赫兹高场产生方面的突破性工作，该项目将建立极端太赫兹光-物质相互作用的新学科。