No abstract

Third‐order optical polarizability near deep centers in ZnS is experimentally investigated for the case of ultrashort light pulses at low temperature of the sample. Dispersion of the optical nonlinearity is characterized with resonant lines located at 16660, 17110, and 17540 cm−1. Higher resolution of the polarization four‐photon spectroscopy is demonstrated, which delivers additional information about the energy structure. Use of the mode‐locked laser pulses allows to extend the range of the pump intensity applied to the single crystal. Comparing of the experimental results with a conventional method is performed.