Nonlinear light absorption in GaSe crystals at the fundamental absorption edge

Abstract The nonlinear light absorption at the fundamental absorption edge for high excitation intensities in GaSe has been investigated experimentally. The bleaching of band-edge absorption which manifests itself as an apparent blue shift of the absorption edge can be interpreted on the base of bandfilling nonlinearities. It is shown that the observed negative absorption change in GaSe crystal in the basis of optical amplification and the semiconductor laser.