Nonlinear focusing of weak beam by another high power laser

Abstract

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.