  We studied experimentally and theoretically the interaction of lasing modes
in random media. In a homogeneously broadened gain medium, cross gain
saturation leads to spatial repulsion of lasing modes. In an inhomogeneously
broadened gain medium, mode repulsion occurs in the spectral domain. Some
lasing modes are coupled through photon hopping or electron absorption and
reemission. Under pulsed pumping, weak coupling of two modes leads to
synchronization of their lasing action. Strong coupling of two lasing modes
results in anti-phased oscillations of their intensities.
