Influence of nanoparticle dispersion in a transparent liquid on the spatial characteristics of a four-wave radiation converter

The spatial characteristics of a four-wave radiation converter in a transparent heterogeneous polydisperse medium are studied in this paper considering the nanoparticle flow caused by the gravity action with a normal size distribution of particle. Three ranges of average nanoparticle radii (small, intermediate and large), for which different types of spatial spectra of the object waves are characteristic, are distinguished. Shown that in the range of small average nanoparticle radii an increase in the standard deviation leads to an increase in the half-width of the spatial frequency band cut out by a four-wave radiation converter from the spatial spectrum of the object wave. In the range of intermediate average nanoparticle radii an increase in the standard deviation can lead to both an increase and a decrease in the width of the «ring» cut out by a four-wave radiation converter. At large average nanoparticle radii a change in the standard deviation doesn’t affect the spatial selectivity of the four-wave radiation converter.