Nonlinear excitonic susceptibilities of semiconductors at high levels of excitation

The hysteretical behavior of imaginary and real parts of the semiconductor susceptibility in the exciton range of spectrum taking into account the exciton-photon and elastic exciton- exciton interaction in the pump-probe regime depending on the intensity and frequency of the strong pump laser pulse and on the frequency of the test pulse is studied. The conditions of the emergence of the damping suppression and test pulse gain are determined. The abrupt red and blue shifts of the spectral position of the exciton absorption band depending on the intensity of the pump pulse are predicted.