PROPAGATION OF GAUSSIAN BEAMS IN A NONLINEAR MEDIUM

We investigate the propagation of cw (continuous wave) circularly symm etric Gaussian beams in a nonlinear saturable medium using a modified variational approach. We find the equations that describe the characte ristics of the beam, solving them analytically in various regimes. We also determine the conditions under which these solutions may be stabl e in two transverse dimensions. Finally, we solve these equations nume rically in the case of loss, comparing them with the lossless analytic al solutions in the limit of small losses.