The time characteristics of a four-wave radiation converter on thermal nonlinearity in the scheme with codirectional pumping waves

An expression for the time response of degenerate four-wave radiation converter on thermal nonlinearity has been obtained for the scheme with codirectional pumping waves with undepleted pump approximation. The time dependence of spatial spectrum of object wave has been analyzed. It has been shown, that the increase of the angle between pumping waves weakly influences on the outlet time of half-bandwidth of spatial frequencies on steady value at the plane of pumping waves. On the other hand the outlet time of half-bandwidth of spatial frequencies on steady value decreases at the plane whith is perpendicular to pumping waves.