Nonlinear Optical Interactions in Rb-Filled Photonic Band-Gap Fibers

光子带隙光纤(PBGF)能够通过衍射而不是全内反射来引导光。这种光纤允许光和气体在空心区同时高度受限。因此，由于其无与伦比的相互作用长度与横截面核心面积的比率，PBGF为光与气体的相互作用提供了与自由空间、聚焦几何结构相比的独特优势。涉及PBGF的拟议工作将需要在两个主要领域进行研究：1)超低功率光物质与Rb原子的相互作用；2)强超短激光脉冲的传输和高次谐波的产生。对于Rb原子的工作，光诱导原子解吸过程将产生高密度蒸汽，这将允许在极低的光强下探索单光子和双光子非线性相互作用。在高次谐波产生方面的努力将探索利用中等脉冲能量的飞秒激光脉冲在深紫外光中产生光的可能性，方法是将基频场和谐波场都限制在核心内，并使用准相位匹配技术。这样的系统将立即应用于创建基于紧凑型光纤的紫外线和极紫外线光源，这是使用传统的石英玻璃纤维无法实现的。由这笔资金支持的研究生将为理解光与物质的广泛相互作用奠定基础，并将获得表征这种相互作用所需的实验技能。此外，每年有一到两名本科生将在PI的实验室从事与这项研究工作相关的项目，并获得他们在光学物理方面的第一次研究经验。PI和博士生将通过NSF资助的纳米系统中心物理教师研究所(CIPT)和康奈尔材料研究中心广泛参与康奈尔大学的外联活动。此外，PI将继续为高中教师和学生举办与光学有关的研讨会。

Photonic band-gap fibers (PBGF) are able to guide light via diffraction rather than by total internal reflection. Such fibers allow for simultaneous high confinement of light and a gas in a hollow-core region. As a result, PBGF's offer a unique advantage over free-space, focused geometries for interactions of light with gases due to their unmatched ratio of interaction length to cross-sectional core area. The proposed effort involving PBGF's will entail studies in two main areas: 1) ultralow power light-matter interactions with Rb atoms, and 2) the propagation of intense ultrashort laser pulses and high harmonic generation. For the work with Rb atoms, high density vapors will be produced by the process of light-induced atomic desorption which will allow for exploration of one- and two-photon nonlinear interactions at extremely low light levels. The effort on high-harmonic generation will explore the possibility of generating light in the deep ultraviolet using femtosecond laser pulses at modest pulse energies by confining both the fundamental and harmonic fields within the core and through use of quasiphasematching techniques. Such a system would have immediate applications in the creation of compact fiber-based ultraviolet and extreme ultraviolet sources, which cannot be realized using conventional silica glass fiber.The graduate students supported by this funding will develop a foundation for understanding a wide range of interactions of light with matter and will acquire the experimental skills necessary for characterizing such interactions. In addition, one or two undergraduates per year will work in the PI's laboratory on projects related to this research effort and gain their first experience of performing research in optical physics. The PI and the PhD students will participate extensively in outreach activities at Cornell via the NSF-funded Center for Nanoscale Systems Institute for Physics Teachers (CIPT) and the Cornell Center for Materials Research. In addition, the PI will continue to deliver optics-related seminars to high-school teachers and students.