FOCUSING OF LASER-RADIATION OUTSIDE NONLINEAR CRYSTAL IN 2ND HARMONIC-GENERATION IN THE REGIME OF STRONG ENERGY EXCHANGE

One of the mechanisms of self-effect in a second-order nonlinear medium, namely the change of the phase of the radiation at the main frequency during second harmonic generation, is considered theoretically. An analytical dependence of the phase on the crystal length, the radiation power density, the nonlinearity of the crystal and the wave distuning, has been obtained. By means of numerical modeling, it is shown that this mechanism should be taken into account in many important cases along with the other self-effect mechanisms.