2-PHOTON ABSORPTION-COEFFICIENT MEASUREMENTS IN ZNSE-ZNS0.18SE0.82 STRAINED-LAYER SUPERLATTICES

The two-photon absorption (TPA) coefficient alpha((2)) of ZnSe-ZnS0.18 Se0.82 strained-layer superlattices has been measured in different sam ples at excitation energies related to heavy- and light-hole excitons associated with n = 1, 2 subbands in the TE polarization. A comparison between the experimental results and the predictions of analytical th eories on TPA processes including quasi-bidimensional excitonic effect s has been carried out. A satisfactory agreement with the numerical va lues has been shown by one of these theories. Finally, the imaginary p art of the third-order susceptibility chi(l)((3)) has been evaluated f rom the alpha((2)) experimental values.