Femtosecond Four-Wave Mixing Spectroscopy on CdS Crystal

Femtosecond four-wave mixing coherent specstroscopy in CdS crystal on 790 nm at room temperature is analyzed. It is stated that the optical dephasing time is equal to 180 fs. Some specific features of the coherent responses' decay curves indicate that this optical dephasing is due to exciton-exciton interaction. The stimulated photon echo decay curves appear to have a fast decay component (the time constant of approximately 4.5 ps), in case when the energy of exciting pulses exceeds the threshold value of 0.4 $\mu\mathrm J$.