Cheng Y-H, Wahlstrand J K, Jhajj N, Milchberg H M
Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA.
Opt Express. 2013 Feb 25;21(4):4740-51. doi: 10.1364/OE.21.004740.
Femtosecond laser pulses filamenting in various gases are shown to generate long- lived quasi-stationary cylindrical depressions or 'holes' in the gas density. For our experimental conditions, these holes range up to several hundred microns in diameter with gas density depressions up to ~20%. The holes decay by thermal diffusion on millisecond timescales. We show that high repetition rate filamentation and supercontinuum generation can be strongly affected by these holes, which should also affect all other experiments employing intense high repetition rate laser pulses interacting with gases.
飞秒激光脉冲在各种气体中形成丝状，结果表明会在气体密度中产生寿命长的准稳态圆柱形凹陷或“空洞”。在我们的实验条件下，这些空洞直径可达数百微米，气体密度凹陷可达约20%。这些空洞通过热扩散在毫秒时间尺度上衰减。我们表明，高重复率丝状化和超连续谱产生会受到这些空洞的强烈影响，这也会影响所有其他使用强高重复率激光脉冲与气体相互作用的实验。
