CAREER: Coherences and Nonlinear Interactions in Molecular Infrared Polaritons

非技术描述：分子尺度上的物质和光之间的相互作用可以产生一种叫做极化子的新型物质粒子。极化子具有独特的性质，使它们在广泛的社会相关应用中发挥作用，包括医学，化学传感和国土安全，仅举几例。虽然对某些波长的光的分子-光相互作用产生的极化子的性质和应用进行了研究，但对电磁波谱中红外部分波长的光的极化子所知相对较少。本项目利用超快激光研究中红外区极化子的基本性质，旨在了解和控制极化子之间的相互作用。这项基础研究的结果预计将有助于化学传感、材料开发和黑暗可视化等新技术能力的最终发展。教育计划的核心内容包括开发一门针对一年级和二年级本科生的光子材料研究在线课程。该课程旨在帮助许多学生克服对数学和科学主题的恐惧，并吸引更多不同群体的学生进入材料研究领域。此外，该项目通过与一所历史悠久的黑人学院和大学（HBCU）的一名教员合作，为在加州大学圣地亚哥分校（UC San Diego）参与暑期研究活动的少数族裔学生建立了一个渠道。技术描述：极化子是由光子和物质激发之间的强耦合产生的杂化粒子。该项目的科学目标是“在芯片上”理解和控制多个分子红外极化子的相干性和非线性相互作用。该成果将使中红外光子器件，如中红外光调制器、波导和激光器成为可能，这对于实现医学和材料工业的芯片上实验室中红外化学传感至关重要。极化子的研究在可见光和太赫兹波段提供了新的光子应用，但在中红外波段却没有。然而，中红外偏振光子器件是发展实验室芯片化学传感的关键。中红外极化子的相干寿命、空间相干和非线性相互作用等基础知识仍然不清楚，这阻碍了中红外极化子光子应用的发展。为了提高对中红外极化子的基础知识，研究小组计划在两个重要方面开展工作：(1)将中红外极化子的相干性推进到分子振动的自然相干寿命之外，打破目前限制中红外光子用于光子电路和分子传感的限制。(2)“芯片上”的相干和耦合可区分的多个极化，为创建多色光子器件的多耦合量子态相干叠加打开了大门。此外，所开发的新型超快中红外光谱成像可以推广到其他中红外光子研究中。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Description: Interactions between material at the molecular scale and light can produce a new type of material particle called a polariton. Polaritons have unique properties that make them useful in a broad array of societally relevant applications, including medicine, chemical sensing, and homeland security, to name just a few. While the properties and applications of polaritons resulting from molecule-light interactions for some wavelengths of light have been investigated, relatively less is known about polaritons associated with light at wavelengths in the mid-infrared part of the electromagnetic spectrum. This project uses ultrafast lasers to investigate the fundamental properties of polaritons in the mid-infrared regime, and aims to understand and control interactions among polaritons. The results of this fundamental research are expected to contribute to the eventual development of new technological capabilities in chemical sensing, materials development, and visualization in the dark. Central elements of the education project include development of an online course in photonic materials research aimed at first- and second-year undergraduate students. The course is designed to help overcome many students' fears about math- and science-heavy topics, and to attract a more diverse group of students to the field of materials research. In addition, this project establishes a pipeline for engaging underrepresented minority students in summer research activities at UC San Diego, through collaboration with a faculty member at a historically black college and university (HBCU).Technical Description: Polaritons are hybrid particles resulting from strong coupling between photon and material excitations. The scientific aim of this project is to understand and control the coherences and nonlinear interactions of multiple molecular infrared polaritons, 'on a chip'. The outcome would enable mid-infrared photonic devices, such as mid-infrared optical modulators, waveguides, and lasers, that are crucial for realizing lab-on-chip mid-infrared chemical sensing for the medical and material industries. Polariton research has provided novel photonic applications in the visible and THz regimes, but not in the mid-infrared regime. Yet, mid-infrared polariton photonic devices are critical in developing lab-on-chip chemical sensing. Fundamental knowledge, such as coherent lifetime, spatial coherences, and nonlinear interactions of mid-infrared polaritons remains unclear, which prevents mid-infrared polariton photonic application developments. To advance basic knowledge of mid-infrared polaritons, the research team plans to work on two important aspects: (1) Coherence of mid-infrared polaritons is pushed beyond the natural coherence lifetime of molecular vibrations, breaking limits that currently constrain the use of mid-infrared photons for photonic circuitry and molecular sensing. (2) Coherent and coupled multiple distinguishable polaritons 'on a chip' can open the gateway for creating coherent superpositions of multiple coupled quantum states for multi-color photonic devices. In addition, the novel ultrafast mid-infrared spectroscopic imaging to be developed can be extended into other mid-infrared photonic studies.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.