飞秒激光成丝若干新效应研究进展

Several new phenomena in femtosecond laser filamentation

介绍飞秒激光成丝物理模型,重点结合本课题组近期研究发现,评述飞秒激光成丝研究在高阶克尔效应的验证、远程空气激光的发展以及时空聚焦技术在光丝远程操控等方面的最新进展.同时指出尽管飞秒激光成丝过程的基本物理图像已逐渐清晰,但此领域仍存在许多挑战,如成丝过程中高阶克尔效应不可忽略,促进现有的成丝基本模型进一步完善发展;飞秒激光成丝过程中产生的基于谐波种子放大的远程空气激射新现象,其产生机制尚不明确;在成丝操控方面,针对飞秒光丝形态及光丝中光场时空分布的有效调控,已成为当前研究热点.

Beginning with an introduction of the physical model of femtosecond laser filamentation widely accepted today, this paper reviews the latest advances we have achieved in the studies of femtosecond laser filamentation, in- cluding an experimental verification of higher-order Kerr effect, investigations of remote lasing generated in air, and development of sptiotemperal focusing technique for remote manipulation of femtosecond laser filament. Our findings point out that although a seemingly complete picture of the fundamental processes in the femtosecond laser filamenta- tion has been established, there are still many challenging problems to be solved. For example, recent experiments show that a negative higher-order Kerr effect cannot be ignored during the filamentation, showing the incompleteness of the current understanding on the femtosecond laser filamentation; the physical mechanism of lasing action in air induced by femtosecond laser filamentation has been still unclear; and new methods for fully manipulating both the profiles of femtosecond laser filaments and the spatiotemporal properties of the light fields inside the filaments have yet to be developed. These facts conclude that this field is still full of opportunities for innovation.