Interferometry of spontaneous parametric down conversion

Summary form only given. The interference of spontaneous radiation emitted from two macroscopic regions (a nonlinear analogy of the Mach-Zehnder interferometer) is considered. The interferometer is based on two nonlinear crystals, excited in series by a common laser pump. The crystals are separated by a layer with an unknown dispersion law. It was shown that the frequency-angular intensity distribution of scattered light formed in the far zone contains quantitative information about dispersion properties of the substance placed between two nonlinear properties. The specific future of this effect is that the phase of the resulting intensity distribution depends on the phase shift of all three frequencies that are involved in the interference process (pump frequency, signal and idler frequencies of spontaneous radiation). Due to the quantum nature of this effect it is possible to obtain information about dispersion properties of the intermediate media in the IR (frequency range of idler wave) from the visible spectrum (signal wave). Thus there are two ways for application of this effect also known as nonlinear or three frequencies interference. The effect allows one to manipulate the structure of biphoton fields, based on the nonuniformity of the interaction region, and it also allows one to study the dispersion of gases, liquids and solids in a wide spectral range using the well-known spectroscopy of spontaneous parametric scattering or scattering by polaritons.