Induced focusing from counter-propagation of two optical beams in self-defocusing media

In this paper, it is numerically simulated that two optical beams with one's intensity much stronger than the other propagate simultaneously in opposite directions in a two-dimensional self-defocusing nonlinear medium. The results show that the weaker probe beam can be induced to focus due to cross-phase modulation from the stronger pump beam under certain conditions. The effects of the four parameters, that is, the specimen length, the initial transversal distance between the beam centers, the initial pump amplitude, and the initial probe amplitude, on the focusing of the probe beam are also discussed, and it is found that some of the parameters have optimum values which result in the strongest focusing. (C) 2004 Elsevier B.V. All rights reserved.