Induced versus parametric scattering processes in potassium

Stimulated and enhanced two-photon emissions from excited states in potassium have been observed. This emission is primed by stimulated electronic Raman radiation generated by scattering of a giant pulse ruby radiation. Four-photon parametric processes also take place. The two processes can be distinguished by tuning the laser frequency. Most of the emitted radiations are plane-polarized. A pumping model is proposed explaining the required population inversions and the polarization properties of the radiations.