Interferometry of spontaneous parametric scattering

Summary form only given. The interference of spontaneous radiation emitted from two macroscopic regions (nonlinear analogs of the Mach-Zehnder interferometer) is considered. The interferometer is based on two nonlinear crystals LiNbO/sub 3/-xMgO 5%, excited in series by a common laser pump beam. The crystals are separated by a layer with unknown dispersion law. It was shown that the frequency-angular intensity distribution of scattered light formed in the far field zone contains quantitative information about dispersion properties of the substance placed between two nonlinear crystals. We discuss the possibilities of the technique, which allows to study the dispersion of gases, liquids and solids in a wide spectral range by the well-known spectroscopy of spontaneous parametric scattering or scattering by polaritons However nonlinear interferometry does not require that intermediate substance has quadratic susceptibility.