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

ECS-0545417L。Zurk波特兰州立大学太赫兹(THz)成像是一项前景看好的新技术，随着产生THz脉冲的超快光学激光的进步，科学界对这一潜力的探索终于成为可能。这项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，这些模型被集成到一个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互动学习工具，并为本科生融入研究过程提供一条途径。这项研究的成功完成将使人们在理解太赫兹传播特性方面取得重大进展，特别是在太赫兹光谱在爆炸物探测和医学成像方面的应用。计算模型还将促进基于计算机的可视化工具的开发，这些工具将把研究纳入讲课和实验室环境。这一过程将用全面的指导方针记录下来，并根据对学生学习和发展的影响进行量化评估。这些将通过在互联网上张贴和在美国工程教育学会等教育期刊上发表来传播给更广泛的教育界。拟议的研究包括开发用于从随机介质中预测THz场统计的计算软件，并将这一计算纳入系统表征中，其中包括量子力学(QM)框架和THz脉冲产生的频谱。因此，这项活动需要：1)开发基于粒子的和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波长发生的粒子共振和色散；3)应用傅立叶合成，将QM、EM和系统光谱分量结合起来，以生成时域响应；4)通过与华盛顿大学(UW)THz测量设施的合作实验活动，验证结果模型；以及5)将模型纳入教育活动。拟议的活动具有实质性的智力价值。它将大大提高对太赫兹波传播的理解，同时提供对随机介质模型和电磁散射计算技术的严格评估。该代码将在波特兰州立大学(PSU)装备精良的西北电磁和声学研究实验室(NEAR-Lab)开发，并将利用PI之前的研究活动，即PI开发随机介质模型和散射公式，用于通过密集堆积的球体系统进行微波传播。该方法的一个独特组成部分是合成时间域响应，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，并提供探索和评估各种材料的THz成像潜在应用的能力。拟议的活动将促进科学理解，同时通过开发可视化工具和将本科生纳入(和评估)研究过程的附带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(妇女)PI的领导为妇女提供工程学方面的榜样，加强妇女在每个机构中的参与。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.