Wavelength Scaling of Plasma and Spatio-Temporal Dynamics of Laser Filamentation in Solids

本研究项目将提高对固体中激光成丝的物理机制和时空动力学的理解。激光成丝是高功率激光脉冲在气体、液体或固体材料中传播时，由于激光在材料中引起的变化而使脉冲的自聚焦得到平衡，从而实现自导向。这种非凡的现象有许多应用，如桌面紫外线和x射线的产生，闪电引导，降雨，对癌细胞的选择性放射治疗，空气中的长寿命波导，以及污染物的遥感。这个项目还将向传统上在科学领域代表性不足的群体，如祖父母领导的农村家庭，推广基础科学教育。当由光学克尔效应引起的自聚焦被由材料电离和/或其他非线性机制引起的离焦平衡时，高功率激光脉冲的自导向就是激光成丝。虽然激光成丝的研究主要是利用近红外和可见波长，但近年来超快激光技术的进展使得利用更长的波长（如中红外和长波红外）研究激光成丝成为可能。在本项目中，固体中的激光细丝将通过直接测量细丝内的等离子体密度进行实验研究，实验指导是激光物质相互作用的三维计算机模拟。该项目将影响基于灯丝的技术，如用于光谱学和光通信的新型超宽带和超短光产生。

This research project will improve the understanding of the physical mechanisms and the spatio-temporal dynamics of laser filamentation in solids. Laser filamentation is self-guidance of a high-power laser pulse propagating through a gas, liquid or solid material when self-focusing of the pulse is balanced by defocusing due to the laser-induced modifications in the material. This remarkable phenomenon finds a lot of applications such as table-top ultraviolet and x-ray generation, lightning guiding, rainmaking, selective radiotherapy on cancer cells, long-lived waveguides in air, and remote sensing of pollutants. This project will also promote basic science education to groups, such as grandparent-led rural families, who have been traditionally underrepresented in science.Laser filamentation is self-guidance of a high-power laser pulse when self-focusing due to the optical Kerr effect is balanced by defocusing due to material ionization and/or other nonlinear mechanisms. Although laser filamentation has been studied mainly using near-infrared and visible wavelengths, recent progress in ultrafast laser technology enables the investigation of laser filamentation using longer wavelengths such as mid-infrared and long-wavelength infrared. In this project, laser filamentation in solids will be experimentally studied by measuring plasma densities directly inside the filaments, with the experiments guided by 3-dimensional computer simulations of laser matter interactions. The project will impact filament-based technology such as new ultrabroadband and ultrashort light generation for spectroscopy and optical communications.