CIF: Small: Impact of radiation trapping on sensing and communication systems in the THz, infrared, and optical regime - foundations, challenges, and opportunities

CIF：小：辐射捕获对太赫兹、红外和光学领域传感和通信系统的影响 - 基础、挑战和机遇

• 批准号: 2320937
• 负责人: Andreas Molisch
• 金额: $ 60万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-10-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2320937&HistoricalAwards=false
• 关键词: CIF; Small; Impact; radiation; trapping

When electromagnetic radiation is sent through a gas, specific frequencies can be absorbed, and then re-emitted. The re-emitted radiation can be re-absorbed somewhere else in the gas, re-emitted there, and so on. This absorption/re-emission is known as “radiation trapping”. Because each absorption/re-emission induces a delay and can change the direction as well as induce a slight frequency change, radiation trapping changes the fundamental characteristics of the radiation – in other words, the radiation arriving at a detector has characteristics that are different from that of the radiation that was originally incident on the gas. As mentioned above, radiation trapping happens mainly at specific (very high) frequencies. As modern wireless systems are moving to higher and higher frequencies, there are thus more situations where radiation trapping is important. Wireless systems in those frequency ranges might be used for communication, sensing, or both. In any of these cases, it is important to analyze the impact of radiation trapping – either to simply assess its impact, to find ways to mitigate its detrimental effects, or to actively exploit it. This project pursues an in-depth investigation of both the fundamentals of radiation trapping and its effects on next-generation wireless communications and sensing. The results of these investigations will form a foundation for future wireless system design in these ultra-high-frequency regions, and will be broadly disseminated. Furthermore, significant outreach activities, aimed at broadening the participation in this research area, are planned. The radiation trapping process has important consequences for the properties of the resonance radiation emerging from the gas. Firstly, the line shape is distorted: since photons at the center frequency of the absorption line “see” a high absorption coefficient, the probability of reaching the detector is low, while photons in the “wings” of the line shape can escape more easily. Secondly, the emerging radiation suffers from both delay dispersion, frequency dispersion (the re-emitted frequencies are shifted from the absorbed frequencies), and spatial dispersion (photons can be re-emitted in any direction, though there can be a nontrivial relationship between directional dispersion and frequency dispersion). The project will start by investigating the interaction of resonance radiation with molecular transition and the interaction between Orbital Angular Momenta (OAM) radiation with atoms and molecules. Solution methods for the fundamental equation of radiation trapping, the Holstein equation, will be investigated for conditions that are practically relevant for transmission in (Earth) atmosphere. The project then will investigate how trapping can impact sensing systems. Finally, the implications for communications systems, including multi-carrier and single-carrier systems, will be investigated. The project takes an interdisciplinary approach, combining insights from atomic/molecular physics, chemical physics, communication theory, wireless system design, and experimental design.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

当电磁辐射穿过气体时，特定频率可以被吸收，然后重新发射。重新发射的辐射可以被气体中的其他地方重新吸收，在那里重新发射，等等。 -发射被称为“辐射捕获”，因为每次吸收/再发射都会引起延迟，并且可以改变方向并引起轻微的频率变化，因此辐射捕获改变了辐射的基本特性——换句话说，就是辐射。到达一个入射探测器具有与最初在气体上移动的辐射不同的特性，如上所述，辐射捕获主要发生在特定（非常高）的频率，因此现代无线系统的频率越来越高。在这些频率范围内的无线系统可能用于通信、传感或两者，分析辐射捕获的影响非常重要——无论是简单地评估其影响，还是对辐射捕获的影响进行分析。找到减轻其有害影响或积极利用它的方法。该项目深入研究辐射捕获的基本原理及其对下一代无线通信和传感的影响，这些研究的结果将为这些超高频区域的未来无线系统设计奠定基础。此外，计划开展旨在扩大该研究领域参与的重大外展活动，辐射捕获过程对气体产生的共振辐射的特性具有重要影响。扭曲：因为光子位于中心吸收线“见”的频率吸收系数高，到达探测器的概率低，而线形“翅膀”中的光子更容易逃逸。 其次，新出现的辐射同时受到延迟色散和频率的影响。色散（重新发射的频率从吸收的频率偏移）和空间色散（光子可以在任何方向重新发射，尽管方向色散和频率色散之间可能存在重要关系）该项目将启动。通过研究共振辐射与分子跃迁的相互作用以及轨道角动量（OAM）辐射与原子和分子之间的相互作用，将研究辐射捕获基本方程（荷斯坦方程）的求解方法，以了解与实际相关的条件。最后，该项目将研究捕获如何影响传感系统，包括多载波和单载波系统，该项目将采用跨学科方法，结合见解。从原子/分子物理学、化学物理学、通信理论、无线系统设计和实验设计。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。