On the possibility of studying the fraction of inhomogeneities in optical nonlinear media using time-resolved inline digital holography

An approach to determining the fraction of inhomogeneities of the optical nonlinear properties of a transparent medium characterized by a spatial variation of nonlinear coefficient of refractive index $n_2$ has been considered. The data has been recorded by the method of inline digital holography with femtosecond time resolution, during which, as the time delay between the pump and the probe pulses changes, a series of inline digital probe holograms has been recorded in the Fresnel diffraction zone. The digital holograms contain Fresnel diffraction patterns with the information about induced degenerate noncollinear phase modulation formed in the presence of inhomogeneities of optical nonlinear properties. The developed algorithm is based on the calculation of the diffraction patterns Fourier spectrum and analysis of the intensity at zero spatial frequency. The proposed method has been validated in numerical simulation.