非线性介质中强光对弱光聚焦的控制研究

Nonlinear focusing of weak beam by another high power laser

从理论和实验上分析了强光控制弱光脉冲聚焦的方法,该方法可以灵活地控制弱光的聚焦过程和特性.通过研究两光束共同传输,利用强抽运光在相互作用时为弱探测光提供诱导非线性效应,从而使弱探测光发生聚焦.得到了在抽运光保持不变情况下探测光的解析解,并在实验上得到验证.进一步研究了强抽运光对弱探测光焦点位置的影响.结果显示:通过改变抽运光功率、束宽能够有效地控制弱探测光的聚焦过程和焦点位置.

In this paper, we theoretically and experimentally investigate the controllable nonlinear focusing of the weak laser beam on the basis of the induced nonlinear effects by another strong pump laser beam. When couple laser beams co-propagate in the Kerr medium, it is possible to change the refractive index by the pump beam, and the locally changing medium in turn modifies the weaker probe beam. Depending on cross-phase modulation theory, we obtain an exact analytical solution to the model under the approximate condition and qualitatively verify it in experiment. The results show that the weaker probe beam can be induced to focus at any position due to induced nonlinear effects from the stronger pump beam under certain conditions.