Author Affiliations
Abstract
Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
Bespalov-Talanov theory on small-scale self-focusing is extended to include medium loss for a divergent beam. Gain spectrum of small-scale perturbation is presented in integral form, and based on the derived equations we find that the cutoff spatial frequency for perturbation keeps a constant value. The larger the medium loss is, the smaller the fastest growing frequency and the maximum gain of perturbation with defined propagation distance are. For a given medium loss the maximum gain of perturbation becomes larger, while the fastest growing frequency becomes smaller as the propagation distance becomes longer. Furthermore, physical explanations for the appearance of these features are given.
小尺度自聚焦 最快增长频率 最大增益 190.3270 Kerr effect 190.3100 Instabilities and chaos 140.3440 Laser-induced breakdown Chinese Optics Letters
2010, 8(2): 210
由光束在吸收(增益)介质中传输的非线性近轴波方程,推导出了光束在两种介质中传输时,由于小尺度调制的非线性增长所引起的小尺度自聚焦所满足的微分方程.进而讨论了光束在增益介质中传输时产生的小尺度自聚焦特性,得出了其截止频率、最快增长频率、纹波的积分指数增益等特性随各参量的变化,并推出了小尺度自聚焦产生的最小传输距离.
B-T理论 小尺度自聚焦 截止空间频率 最快增长频率 积分指数增益
1 四川大学,光电科学系,四川,成都,610064
2 中国工程物理研究院,激光聚变研究中心,四川,绵阳,621900
由光束在非线性介质中传输所满足的近轴波方程,应用Bespalov- Talanov(BT)理论,导出了光束在两种介质中传输时,小尺度不稳定增长所遵循的微分方程.通过对比分析介质的增益和损耗对高功率激光的小尺度自聚焦行为的不同影响,得出了截止频率、最快增长频率、纹波的积分指数增益等特性随各参量的变化,求得了最大和最小的纹波增长的距离,以及介质的增益和损耗特性对成丝距离的影响.
BT理论 小尺度自聚焦 最快增长频率 积分指数增益 最大增益因子 Bespalov Talanov theory small scale self focusing the fastest increase frequency integral exponential gain maximal gain factor
