Correlations in far field of photons emitted by parametric fluorescence

The fundamental research of the parametrical fluorescence is discussed. We start with the mathematical model. We have included the final size of nonlinear crystal, the chirped pump pulse of Gaussian elliptical beam in the model. We have verified the numerical results experimentally. We have used two different methods. First one used ICCD camera, and second one, scan by Hong-Ou-Mandel interferometer.