Transient stimulated four-photon parametric scattering in the case of pumping with adiabatic pulses

A theoretical investigation is made of stimulated four-photon parametric scattering in a medium of two-level atoms pumped by high-intensity ultrashort pulses. A simple dependence of the gain on the phase mismatch, pumping duration, and length of the interaction region is obtained. The spectral and angular distributions of the scattered radiation are considered and the features of these distributions associated with the transient nature of the process are discussed.