Fluctuations in the number of photons above the bifurcation point in the process of third harmonic generation

The quantum fluctuation of the number of photons of the fundamental mode and of the third harmonic in the process of intracavity generation of the third harmonic in the region of unstable behavior of the system is studied. The distribution functions of the number of photons of interacting modes, as well as the function of the joint distribution of the number of photons of the fundamental mode and of the third harmonic, are calculated in the positive P-representation.