抄録
Multi-photon spectroscopy on some II–VI semiconductors was carried out by monitoring the transmitted intensity of a probe light under the application of a laser light. Both the increase and decrease of the transmitted intensity were observed after the laser pulse. They correspond to the change of an absorption coefficient by the order of 10−3 cm−1.
In comparison with the studies of the recombination radiation of excitons excited by two photons of the laser, these effects are considered to be due to the carriers created by two-photon absorption and captured by the trap states in the band gap. These states which are impurity levels or lattice defects are generally located at the lower energy side of the free-exciton recombination states.
Small change of the optical absorption in a thick sample is detected by this method.
