Induced focusing from co-propagation of a pair of bright-dark optical beams in self-defocusing Kerr media

Explored is the induced focusing in the bright-probe-and-dark-pump geometry in a two-dimensional self-defocusing Kerr medium. It is numerically simulated that a bright probe beam and a dark pump beam co-propagate in the medium. The numerical results show that under some conditions the weak probe beam can be induced to focus due to cross-phase modulation by the intense dark pump beam. Further simulations show that the strongest focusing can be obtained by choosing suitable propagation parameters. The effect of the finite bright background on the induced focusing is also discussed.