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ab-initio description of optical nonlinearities in femtosecond filaments

飞秒灯丝光学非线性的从头算

基本信息

批准号：
229103282
负责人：
Dr. Carsten Brée
金额：
--
依托单位：
Weierstraß-Institut für Angewandte Analysis und Stochastik (WIAS)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2015-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/229103282?language=en
关键词：
ab initio description optical nonlinearities

项目摘要

Femtosecond filaments are self-organized strings of light and free electric charges. The electric field strength in these filaments comes closeto the atomic field strength.Therefore, laser filamentation, together with high-harmonic generation, is oneof the most extreme scenarios in nonlinear optics, with a largenumber of effects acting simultaneously in the spatial as well as inthe temporal domain. While numerical modeling is quite advanced,recently, the commonly accepted picture of filamentation has beenchallenged by experimental reports that indicate a previouslyunderestimated effect resulting from higher-order electronicnonlinearities which may overrule plasma effects. While this reporthas given rise to vivid discussions, a rigorous theoreticalunderstanding going all the way back to the quantum mechanicalroots, i.e., the Schr\"odinger Equation is still outstanding. Herewe propose a suite of theoretical tests for the role of high-orderharmonics in nonlinear optics. These tests start with the simplestcase of atomic hydrogen or helium, using non-perturbativetechniques. For more complex and experimentally more relevantscenarios, we plan to use time-dependent density functional theoryto calculate the induced dipole moment. Such rigorous theoreticalinvestigations appear to be the only way to decide whether we reallyhave a new paradigm in Nonlinear Optics or whether old pictures ofplasma effects balancing Kerr effects actually prevail.

飞秒细丝是自组织的光和自由电荷串。这些细丝中的电场强度接近原子电场强度。因此，激光成丝和高谐波的产生是非线性光学中最极端的情况之一，在空间和时域中同时发生大量的效应。虽然数值模拟相当先进，但最近，普遍接受的细丝图受到实验报告的挑战，这些报告表明，以前被低估的效应是由高阶电子非线性引起的，这可能会推翻等离子体效应。虽然这篇报道引起了生动的讨论，但一个严谨的理论理解，一直追溯到量子力学的根源，即薛定谔方程，仍然是突出的。本文提出了一套高阶谐波在非线性光学中的作用的理论检验。这些测试从最简单的氢原子或氦原子开始，使用非扰动技术。对于更复杂和实验更相关的场景，我们计划使用时依赖密度泛函理论来计算诱导偶极矩。如此严格的理论研究似乎是决定我们是否真的在非线性光学中有一个新的范例，或者是否等离子体效应平衡克尔效应的旧图片实际上占上风的唯一方法。