PECASE: Electromagnetic Scattering and Propagation in Random Media at Terahertz Frequencies

ECS-0545417L。太赫兹（THz）成像正在成为一种有前途的新技术，随着超快光学激光器产生THz脉冲的进步，科学界对这种潜力的探索终于成为可能。本研究计划的目标是通过开发先进的电磁（EM）模型来表征宽带太赫兹（THz）脉冲在随机介质中的传播和散射，这些模型将被集成到严格的系统仿真框架中。这些模型还将被用作电磁学教育的交互式学习工具，并为本科生融入研究过程提供途径。该研究的成功完成将导致对太赫兹传播特性的理解取得重大进展，特别是将太赫兹光谱应用于爆炸物检测和医学成像。计算模型还将促进基于计算机的可视化工具的开发，这些工具将研究纳入讲座和实验室环境。该过程将记录与全面的指导方针和定量评估方面对学生的学习和发展的影响。这些将通过发布到互联网和在美国工程教育学会等教育期刊上发表来传播到更广泛的教育界。拟议的研究包括开发计算软件，用于预测来自随机介质的THz场统计数据，以及将该计算并入包括量子力学（QM）的系统表征中，框架和太赫兹脉冲产生的频谱。因此，这项活动需要：1）开发基于颗粒的连续变化的随机介质模型，以表示炸药和生物医学材料的不均匀性，2）扩展EM散射理论，以解释在THz波长处发生的颗粒共振和色散，3）应用傅立叶合成来联合收割机组合QM、EM和系统光谱分量，以生成时域响应，4）通过与华盛顿大学（UW）THz测量设备的合作实验活动验证所产生的模型，以及5）将模型纳入教育活动。拟议的活动具有实质性的知识价值。它将大大推进太赫兹波传播的理解，同时提供了一个严格的评估随机介质模型和电磁散射计算技术。该代码将在PI设备齐全的西北电磁学和声学研究实验室（NEAR实验室）在波特兰州立大学（PSU）开发，并将利用以前的研究活动，其中PI开发随机介质模型和散射公式的微波传播通过密集的球体系统。所提出的方法的一个独特组成部分是合成时域响应的过程，以获得严格推导的端到端集成系统响应，该响应捕获复杂的散射物理，并提供探索和评估THz成像对各种材料的潜在应用的能力。拟议的活动将促进科学的理解，同时通过开发可视化工具和将本科生纳入研究过程（和评估）的伴随程序来丰富教育环境。它将通过共享实验设施促进PSU和UW之间的伙伴关系，并通过（女性）PI的领导为工程领域的女性提供榜样，加强女性在这些机构中的参与。潜在的社会效益确实令人印象深刻，包括检测有害爆炸装置或检测癌症存在的能力。科学成果将通过科学期刊和技术会议广泛传播。

ECS-0545417L. Zurk Portland State UniversityTerahertz (THz) imaging is emerging as a promising new technology, and exploration of this potential by the scientific community has finally become possible with advances in ultrafast optical lasers to generate THz pulses. The goal of this research program is to characterize broadband Terahertz (THz) pulse propagation and scattering in random media with the development of advanced electromagnetic (EM) models that are integrated into a rigorous systems simulation framework.These models will additionally be utilized as an interactive learning tool for electromagnetics education and to provide an avenue for integration of undergraduates into the research process. Successful completion of the research e_ort will result in significant advances in understanding of THz propagation characteristics, with specific focus on application of THz spectroscopy to detection of explosives and to medical imaging. The computational models will also facilitate the development of computer-based visualization tools that will incorporate research into lecture and laboratory environments. The process will be documented with comprehensive guidelines and evaluated quantitatively in terms of the impact on student learning and development. These will be disseminated to the wider educational community by posting to the internet and presentation in educational journals such as the American Society for Engineering Education.The proposed research consists of the development of computational software for the prediction of THz field statistics from random media, and the incorporation of this calculation into a system characterization which includes the quantum mechanical (QM) framework and the spectrum of the THz pulse generation. The activity thus requires: 1) development of particle-based and continuously varying random medium models to represent the inhomogeneities of the explosive and biomedical materials, 2) extension of EM scattering theory to account for particle resonances and dispersion that occur at THz wavelengths, 3) application of Fourier synthesis to combine the QM, EM, and system spectral components to generate the time domain response, 4) validation of the resulting models through a collaborative experimental activity with the University of Washingtons(UW) THz measurement facility, and 5) incorporation of the models into educational activities.Intellectual Merit. The proposed activity has substantial intellectual merit. It will significantly advance understanding of THz wave propagation, while simultaneously providing a rigorous assessment of random media models and techniques for EM scattering calculation. The code will be developed in the PIs well-equipped Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab) at Portland State University (PSU), and will leverage previous research activities in which the PI developed random medium models and scattering formulations for microwave propagation through densely packed systems of spheres. A unique component of the proposed approach is the process for synthesizing the time domain response to obtain a rigorously derived end-to-end integrated system response that captures the complicated scattering physics and provides the ability to explore and assess the potential application of THz imaging for a variety of materials.Broader Impacts. The proposed activity will advance scientific understanding while simultaneously enriching the educational environment through development of visualization tools and an accompanying procedure for the incorporation (and evaluation) of undergraduate students into the research process. It will promote partnership between PSU and UW through shared use of experimental facilities, and strengthen the participation of women in each of these institutions by providing a role model for women in engineering through the leadership of the (woman) PI. The potential societal benefits are truly impressive, including the ability to detect harmful explosive devices or detect the presence of cancer. The scientific results will be broadly disseminated through scientific journals and technical conferences.