Flexible spectrally tunable radiation sources for multi modal spectroscopic analysis

用于多模态光谱分析的灵活光谱可调辐射源

• 批准号: 427211214
• 负责人: Professor Dr. Martin Hofmann
• 金额: --
• 依托单位: Lehrstuhl für Photonik und Terahertztechnologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/427211214?language=en
• 关键词: Flexible; spectrally; tunable; radiation; sources

The long-term vision of this project is to realise a tunable light source for simultaneous multi modal sensor applications in the UV, in the near Infrared, and in the THz-range. Our goal for the application period is to develop a sensor for simultaneous THz- and Raman spectroscopy on the basis of monolithically tunable diode lasers. THz- and Raman spectroscopy address different excitations and the corresponding additional information is interesting for several applications. As an application example, we aim to detect relevant exhaust gases via THz-spectroscopy and soot particles via Raman spectroscopy. One out of many other possible applications of such a sensor is to control packaged food: even through the packaging the quality of the food could be analysed by Raman spectroscopy, and THz spectroscopy would enable to analyse the atmosphere within the package (e.g. water content). If it was possible to realise a two-colour radiation source in which the spectral distance of the two wavelengths could be tuned electrically from 0 to 6.4 nm, one could cover the spectroscopically relevant range von 0 to 3 THz (e.g. for the gases N2O, NO, CO, NO2, SO2 and H2O which are relevant in exhaust processes) by difference frequency generation. With the corresponding spectral distances up to 7nm one could also separate broad Raman features (e.g. of amorphous carbon) from disturbing background like fluorescence or ambient light. Therefore, our project goal is to realise a diode-laser based monolithically integrated radiation source that enables a tunable two-colour operation with up to 7 nm wavelength separation. On the basis of this laser source, we aim to realize a multi-modal sensor which analyses relevant exhaust gases by THz spectroscopy and soot particles by Raman spectroscopy. A basis for this development is to improve the understanding of the laser devices with regard to their lateral design (curvature of waveguides, coupling of arms) and the understanding of the requirements for this light source given by the THz generation and Raman spectroscopy. We chose 830 nm as the center wavelength for the multi-colour diode laser. On the one hand, this is a well established wavelength for Raman spectroscopy which reduces potentially appearing fluorescence, and for which required filter elements are available. A detection of the Raman-spectra for substance identification through spectral fingerprints is possible with Silicon based detectors. On the other hand, this wavelength is also well suited for THz generation with LT-GaAs based photoconductive antennas since it fits well to the absorption spectrum of LT-GaAs.

该项目的长期愿景是实现一个可调光源，用于同时在紫外线、近红外和太赫兹范围内的多模态传感器应用。我们的目标是在单片可调谐二极管激光器的基础上开发一种同时用于太赫兹和拉曼光谱的传感器。太赫兹和拉曼光谱处理不同的激发和相应的附加信息是有趣的几个应用。作为应用实例，我们的目标是通过太赫兹光谱检测相关废气，通过拉曼光谱检测烟尘颗粒。这种传感器的许多其他可能应用之一是控制包装食品：即使通过包装，食品的质量也可以通过拉曼光谱分析，太赫兹光谱可以分析包装内的大气（例如水含量）。如果有可能实现双色辐射源，其中两个波长的光谱距离可以在0到6.4 nm之间进行电调谐，则可以通过差频产生覆盖0到3太赫兹的光谱相关范围（例如，对于废气过程中相关的N2O， NO， CO, NO2， SO2和H2O气体）。随着相应的光谱距离达到7nm，人们还可以从荧光或环境光等干扰背景中分离出广泛的拉曼特征（例如无定形碳）。因此，我们的项目目标是实现一个基于二极管激光的单片集成辐射源，该辐射源可以实现可调的双色操作，波长可达7纳米。在此激光源的基础上，我们的目标是实现一个多模态传感器，用太赫兹光谱分析相关废气，用拉曼光谱分析烟尘颗粒。这一发展的基础是提高对激光设备的横向设计（波导曲率，臂耦合）的理解，以及对太赫兹产生和拉曼光谱给出的光源要求的理解。我们选择830nm作为多色二极管激光器的中心波长。一方面，对于拉曼光谱来说，这是一个很好的波长，可以减少潜在的荧光，并且可以使用所需的滤光片。通过光谱指纹图谱检测物质的拉曼光谱是可能的硅基探测器。另一方面，该波长也非常适合基于LT-GaAs的光导天线产生太赫兹，因为它非常适合LT-GaAs的吸收光谱。