Investigation of the efficiency of second harmonic generation by two types of interaction and optimization of laser radiation parameters

The efficiency of second harmonic generation by oo–e and oe–e interactions of laser radiation characterized by different angular and spectral distributions was investigated under conditions of a strong energy exchange between the fundamental-frequency wave and its second harmonic. The parameters of the laser radiation and of the nonlinear crystal were optimized. It was found that efficient doubling was obtained when the fundamental-frequency laser radiation was polarized linearly and this was true of both the oo–e and oe–e interactions. In the oe–e case the conversion efficiency was very sensitive to the width of the laser spectrum.