Sub-Poisson source of radiation with strong suppression of quantum fluctuations of the intensity

An analysis is made of new possibilities of formation of a sufficiently strong radiation source with a sub-Poisson photon statistics. A nonlinear interferometer, excited by radiation from a degenerate parametric frequency converter, is proposed and analyzed in detail. In such a nonlinear interferometer the transformation due to phase modulation can not only suppress almost completely the classical intensity fluctuations, but also reduce greatly the quantum fluctuations. It is shown that the Fano factor (ratio of the photon number variance to the average number of photons) can under optimal conditions have a value of the order of 0.1.