Two-photon spectroscopy of proustite (Ag3AsS3)

The results are given of an investigation of one of the sections of the two-photon absorption surface of proustite, which made it possible to determine the position of a density-of-states extremum inside an absorption band. The parameters of the energy band structure associated with this extremum were estimated. Measurements of the nonlinear attenuation of light and of the photoconductivity of proustite established that free carriers, released optically from impurity states, played an important role in the absorption process. The lifetime of nonequilibrium carriers was determined. The nonlinear absorption at the neodymium laser frequency was explained entirely by the carrier generation effect.