Effects of phase singularity in the interference of two laser fields with a wide spectrum

The interference of laser beams with a wide spectrum is studied theoretically and numerically. It is shown that in the cross section of such intersecting beams in a small vicinity of zero of the complex mutual coherence function, the change in the argument of the slow amplitude of this function corresponds to the phase singularity. An approximate analytical representation of the mutual coherence function in the vicinity of the singularity point is given. It is found that an average 'funnel' diameter of the modulus of the mutual coherence function that arises in the singularity region does not depend on the intensity of the light beams and remains constant when the longitudinal coordinate changes. The emergence of phase dislocations in the interference pattern is established.